MotoTribology

Grease is a tool used so universally around the world but remains somewhat of a mystery for many of the people who use it. Every motorcycle needs grease at some point and there are several different areas where it is applied. Although grease manufacturing is a somewhat complex process it is somewhat seen as an art and each company’s methods and exact formulas are different. This results in sometimes subtle but sometimes drastic differences in products.

The basic formula for grease is this: base oil, thickener and additives.

  • Base oils can be anything from petroleum to synthetic to plant based oils.
  • There are several different commonly used thickeners. The most common types are lithium, aluminum and calcium sulfonate.
  • The additives used are dependent on the type of grease and the purpose of the grease.

Base Oil:

The base oil composition of a grease will impart a few crucial properties:

Grease-Base-Oil.png?w=404

Table 1: Basic base oil comparison

The reason synthetics are less versatile than non-synthetic base oils is because of synthetic types likes silicone and poly-alyklene glycol (PAG). These types of oil are usually only meant for very specific industrial applications and are unsuitable in many others, so care is needed when selecting grease to avoid these types of synthetics in many instances. With that same reason in mind, additive selection is also more limited with these alternative synthetic options. However, plant based oils are still generally less versatile due to the temperature constraints they are typically limited by to.

Thickener:

Different thickener types have different performance attributes distinct to each type. Here are the most common types of base grease thickeners used for multipurpose motorcycle greases.

Lithium offers a good water resistance, heat tolerance and mechanical stability. It is currently the least expensive type of grease to make so it is very prevalent in the marketplace. The drawbacks of it compared to other types are that it is not completely waterproof and will accept moisture over time.

Aluminum is practically waterproof but is more expensive to manufacture than lithium grease. It offers high temperature stability, but is slightly less mechanically stable than other types.

Calcium sulfonate has excellent high temperature, low temperature and inherent properties that allow it to use fewer additives to obtain certain performance levels. Its water resistance is excellent and it is often compatible with other greases. The big drawback to calcium sulfonate is the price. It is typically much more expensive than either of the other two types to produce.

A grease complex is a variation of the standard base grease that is possible to make with lithium and aluminum. Aluminum and lithium complex greases exhibit higher temperature limits and better mechanical stability than their uncomplexed counterparts.

All three of the grease types listed are often compatible with one another up to around 25% contamination with one type and 75% of the other. Beyond that 3:1 ratio though, incompatibilities are more common and certain properties may be sacrificed if mixed.

There are many other types of thickener types I haven’t mentioned but those are rarely, if ever, used for the types of greases commonly used for motorcycle.

Additives:

Common additives for greases include: anti-oxidation, anti-corrosion, anti-wear and extreme pressure(EP) additives. Additional types are certainly used, but those are going to be found in a lot of greases with perhaps the exception of extreme pressure additives if the grease is not labeled as EP grease.

One last fairly universal additive is dye. Most greases are dyed some color and many people believe these colors mean something. Let me be absolutely clear here so there is no confusion; THE COLOR DOES NOT MATTER. The colors are arbitrary and chosen by the manufacturer for aesthetics and nothing else. They may have their own standards and reasons for why they color certain grease a certain way, but it is not to conform to any industry standard.

Grease Applications & Properties:

Grease has some advantages over oil in certain applications. It can be applied in open areas without a sump or reservoir. It forms a significantly stronger physical barrier on a surface making it more suitable in extreme applications. It can utilize solid lubricants more effectively than liquids can.

There are basically two types of greases commonly used in most motorcycles. They are assembly grease used during engine building or repairs and multipurpose greases for everything else. Multipurpose greases are usually good for bearings, axles, pivots and really any grease point on a bike. Assembly lubricants usually contain a high level of solid lubricants and provide lubrication to machine internals that are normally lubricated by oil or special applications that require a high content of solid additives.

The purpose of assembly lubricants is to provide lubrication on parts that have never been exposed to engine or gear oil yet, so when the bike is started for the first time after maintenance; those parts have some protection before the regular lubricant begins circulating. These assembly greases are usually washed away by the oil and are removed from the system during subsequent oil changes. Another application for these products are areas such as final drives where a high content of solid additives can be beneficial for surface protection.

Most grease points on motorcycles are fairly low load compared to more extreme grease applications in commercial applications. This means specialized grease is rarely needed and a single multipurpose grease is usually able to serve all of those grease points. They go into places that are open and exposed, high load or in places that oil films cannot be maintained. Bearings, axles and chassis linkages are common applications for these greases. They generally will provide extreme pressure protection and decent anti-wear protection. Because they form a physical barrier against water and oxygen, corrosion protection is inherently high, but this is also often boosted further by additives to protect against rust and corrosion. They should maintain a physical barrier to keep out moisture and dirt from these applications that would self destruct very quickly if contaminated. Grease does all of this through both physical and chemical means and there are a few key points to consider when choosing the right grease for your application.

First and foremost is the grease consistency or hardness. This property for grease is just as important as the viscosity is for oil. Using an incorrect grease consistency can quickly result in part failure and under-lubrication.

Grease is categorized into different grades by the National Lubricating Grease Institute (NLGI) scale based on a grease’s penetration test result. Grease penetration is a measurement of the depth at which a calibrated metal cone will penetrate into the surface of grease when dropped form a standard height. Penetration is represented in decimillimeters (tenths of a millimeter), and the penetration is often taken under two different conditions: worked and unworked.

An unworked grease is fresh from the container and has never been used. A worked grease is one that has been put through mechanical stress to simulate usage. The purpose is to indicate the stability of the grease with regards to its consistency. Working grease is a standard process that involves a piston churning the grease a standard number of times using an instrument known as a grease worker. The standard method uses a plunger with 60 holes in it and it is pushed a pulled a total of 60 times in 1 minute.

Grease-worker-v2.png?w=455

Figure 1: Mechanical Grease Worker (please imagine there are 60 holes in the piston face)

After that minute, the grease is considered worked and can now be tested for NLGI consistency. The grades identify significant differences in the hardness or softness of greases. The simplest way I find to describe them is to compare them to common foods.

NLGI-Chart-v2.png?w=390

Table 2: NLGI grades and consistencies.

Another important property of grease is the base oil viscosity. During the manufacture of base grease, the ingredients of the thickener are mixed with oil. When the grease reaction takes place, that oil becomes part of that grease. Typically the higher viscosity the oil, the more heavy duty application it can withstand. However higher viscosity base oils usually limit the low temperature performance, so for general purpose grease, a base oil blend balanced for moderately high and low temperature performance is preferable.

Assembly grease typically contains a high level of solid lubricant meant to withstand high pressure and remain in place in the absence of the regular lubricant that would normally protect the surface. The reason this regular lubricant needs replacing is usually because the machine is rebuilt and hasn’t had the oil circulation system running yet. These greases don’t need to have a very long usable lifespan since they are designed to be used up fairly quickly, washed away by the oil and removed by either a filter or through the next oil change. Therefore, anti-oxidation and long term stability are not key features for assembly lubricants. However, another application for assembly greases comes from the typical high level of solid lubricants. Since these solid lubricants will resist extreme loads there are applications in some bikes that call for a grease like this such as final drive shaft gears.

Grease application is an aspect that a lot of people have difficulty with as well. I often see comments implying to just pump in as much grease as a bearing can hold and that is how much it should use. That advice is almost universally bad. Over-packing a bearing can lead to some very bad failures. Alternatively too little grease is also a problem for more obvious reasons; under-lubrication and all that goes with it being the biggest of them. You can read about the pitfalls of these mistakes and how to avoid them here.

So I hope that gives you a good basic starting point to look at greases and you are now armed with the knowledge to at least ask the right questions when trying to choose between different brands of grease.

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User Feedback




Great article MotoTribology.

Have been using common old "Castrol Boating Grease" (a lithium based grease I now know due to your article is probably just fine) on everything except engine parts.

 

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14 hours ago, BushPig said:

Great article MotoTribology.

Have been using common old "Castrol Boating Grease" (a lithium based grease I now know due to your article is probably just fine) on everything except engine parts.

Thanks! I'm glad you found it useful. :thumbsup: 

A lot of grease points are going to work just fine with a simple multipurpose grease like you are using. The only real trick for most people is finding a grease that stays in place in the worst case scenarios. So if you've found that, you're good to go for just about anything.

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Great info - thank you Mr. moto.   Are you a petroleum engineer?  I actually bookmarked this and will study it more later.

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41 minutes ago, motoxvet said:

Great info - thank you Mr. moto.   Are you a petroleum engineer?  I actually bookmarked this and will study it more later.

No, not a petroleum engineer per se. A petroleum engineer typically works in crude refineries or other plants downstream in the refining process.

My degree is in chemical engineering, but my current occupation is more along the lines of a chemist. I am a product formulator and do R&D for a company that makes lubricants. My specialty is in powersports and marine products.

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I like that grease worker!  Would an end user ever benefit from having something like that to keep their grease mixed before application?

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9 hours ago, kevvyd said:

I like that grease worker!  Would an end user ever benefit from having something like that to keep their grease mixed before application?

Haha! I feel my artwork leaves something to be desired, but I'm glad it got the concept across. No a grease worker's purpose is actually to stress the oil, so if you were to use it on your oil you are stressing it before it even applying it. It isn't anything too extreme but greases should not separate during storage to require any significant mixing. Some greases are very good at resisting oil separation, but some greases exhibit oil separation on the surface of a grease.

When oil does separate on the surface, simply mixing it by hand a little bit until there is no more standing puddles of oil will make it perfectly usable again. No need for anything overly complicated like a grease worker. (I just use a clean screwdriver or my finger)

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mototribo,

do you guys make anything comparable to this?

Schaeffer Manufacturing Co. 02742-029S Moly EP Synthetic Plus Grease NLGI #2

this is the best suited grease for mx bike linkages ive been able to find

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23 hours ago, MotoTribology said:

No, not a petroleum engineer per se. A petroleum engineer typically works in crude refineries or other plants downstream in the refining process.

My degree is in chemical engineering, but my current occupation is more along the lines of a chemist. I am a product formulator and do R&D for a company that makes lubricants. My specialty is in powersports and marine products.

       Reading your article brought me back to a Seminar I attended back in 83?  Went with a fellow Yamaha Mechanic who a few years later became Store Manager for Malcolm’s Shop on Indiana Bl.  Before they moved into the new construction.   Hi, Dave!  Anyway, the Seminar was about oil, Petroleum Base Stock, Co - Polymer Binders, Synthetic Polymers and other oil related information.  It was put on by the Chemical Engineer who created Golden Spectro 100 to 1 crazy synthetic Mix 2 stroke oil.   And he did not make it for Motorcycles or even for a business, but a friend.    Because his good friend owned a Sabb dealership. There were those Sabb Sonnett 3 cyl 2 cycles (some owners had Expansion Chambers built w/straight back downpipes) Tall tires and front wheel drive.  Well that car was made without oil injection or even a tank for oil.  Just a note on the gas door that said something about opening a cardboard sided can of 30 weight motor oil with your handy quick and easy can opener and poor a quart in the gas tank for every 10 gallons. No provision to make it poor into the cap which was essentially horizontal to the ground, no accurate measurement or indication that there was no oil left which would be easy in a tank.

 

       Within little over a month the owner of the dealership came to work on a Monday early and there were 8 or so Sonnett's with "Dead Battery" service tickets.  That is the story about how the Chemical engineer, engineered a Synthetic 2 cycle motor oil that could run at major inconsistent mixtures providing a better outcome.    But IMO (experience) tearing down the Cranks on Dirt Bikes with that oil at 90 or 100 to 1 seemed to have been subject to too much friction heat. Used to be Caster Oil, then Torco not exceeding 20 to 1.   Then even in the time of super unobtainoum factory exotic 1 off aluminum tank 250k machines, Good old 24-1 or 28-1 Yamalube R was in the other Factory team Pits with the Yamaha label torn off the bottles all the way into the 80s, and the closest high ratio mix that seemed actually near safe was BelRay which at 42?-1 you would see a golden coating on the Con Rod that didn't look like it was heated with an oxy acetylene torch.

 

         Silly story over, the take away that I still can recommend to people is with a multi-grade oil the low number is the grade of the Base Oil Stock.  It is stable and essentially the same if processed with the same standards across the board everywhere. What makes a multi-grade oil expensive or not is the quality of the binders ( he called them co-polymers) which allow the stable base oil to increase viscosity with temperature.  So Good Oil is Engineered with Quality made to last till an oil change Expensive Binders, and cheap oil will get a car about 500 to 1000 miles perhaps before the binders break down and it becomes perhaps 10 weight, or 5 if your choose oil even at extreme summer temperatures.   Along the lines of stability, base oil has properties which are stable but it is the things that enter it making it dirty or impure or it would keep working multiple x the recommended change-out.

Finally, the take away is:

"If you are stuck having to buy a quart of oil for your vehicle out in Booneyville or anywhere that it is not high quality and or not anywhere near properly priced.  Purchase a straight grade oil 30 Wt. or 40 Wt. as that will be the viscosity you can count on."+ not waste money.

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21 hours ago, EnglertRacing said:

mototribo,

do you guys make anything comparable to this?

Schaeffer Manufacturing Co. 02742-029S Moly EP Synthetic Plus Grease NLGI #2

this is the best suited grease for mx bike linkages ive been able to find

Yes greases like that are fairly common enough that pretty much everyone makes something similar with regards to the basics (NLGI 2, EP or anti-wear performance) Some companies only deal with synthetics while others use non-synthetics only and others have a mixture of offerings, but either way someone will have what you need if that is the grease being recommended.

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its aluminum base with moly,

which works great for the linkage bearings since they tend to get wet, and are under some pressure

i haven't been able to find many other greases that are comparable

can you recommend some?

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52 minutes ago, EnglertRacing said:

its aluminum base with moly,

which works great for the linkage bearings since they tend to get wet, and are under some pressure

i haven't been able to find many other greases that are comparable

can you recommend some?

I try not to promote any one brand over another, but I'll bend my rules a bit here. This application is perfect for a multipurpose grease. I also like the aluminum complex for this because of its waterproof characteristics, but a lithium complex grease could perform very well too if it is formulated well. The moly is good, but it is likely a bit overkill for linkages unless youa re doing some very extreme riding. The Schaeffer's product boasts a four ball EP result of 315 kgs and a timken load of 60 lbs which are both perfectly fine results, but certainly not unmatched.

If you are happy with the Schaeffer's product and are getting good results, I would be the last person to suggest you change to something else. If for some reason you are unhappy with that product and want to switch, just about every lube manufacturer makes a multipurpose NLGI 2 grease.

To narrow your search down you can focus on aluminum complex greases and to widen your choices, you can ignore the moly content and instead focus on the performance. If the grease you are looking at provides adequate surface protection despite not containing moly, it should be a candidate for you.

Here's a list of potential candidates from companies that are widely available. These are in alphabetical order and are in no way a ranked list. Sorry about that, but some people around here like to pretend that I promote particular brands even though to my knowledge I never have.

Bel-Ray Waterproof Grease

Ipone Waterproof Grease

Royal Purple Ultra-Performance Grease

This is just from a very brief search of aluminum complex greases marketed for motorcycles. I'm sure there are plenty more out there.

If it were me in your place, I wouldn't worry about the moly content and focus on the moisture resistance and wear prevention characteristics. If you have trouble finding data on a product you are considering, I always advocate calling or emailing the manufacturer and asking them your questions directly.

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18 hours ago, Bermudacat said:

When citing specific works, you should always include a reference back to that work, otherwise it looks like plagiarism.

 

Did the Amway oil Training Brochure for New Tribologysts also plagiarize the work of Machinery Lubrication Online ?

http://machinerylubrication.com/Authors/Detail/744

http://machinerylubrication.com/Read/1352/grease-basics

:naughty:

I've made a good habit of ignoring your lies and slander. However, since you are now accusing me of violating a copyright, I suppose I'd prefer readers of my content see that addressed rather than keep myself happy by avoiding responding to an internet troll.

You may want to at least read the articles when you, knowingly, falsely accuse someone of plagiarizing. The article you are referring to is significantly different than the one I wrote. There are certainly similar topics covered since they are both articles about the technical aspects of the basic concepts regarding lubricating grease, but the actual content in the articles is quite divergent from one another.

If you are referring to the consistency chart, those comparisons have been around for a long time. I believe they were first published here: 

Rudnick, Leslie R. (2005). Synthetics, Mineral Oils, and Bio-Based Lubricants: Chemistry and Technology (Chemical Industries). CRC. p. 468.

But as far as I know, industry people, such as myself, have been making those comparisons for decades as an easily understood way to describe grease thickness. So I would very much doubt that anyone has any rightful claim to those comparisons including myself.

I do hope you'll take the time to read content in the future with the open-mindedness to gain knowledge rather than automatically harassing the author with untrue claims. And if you see something truly inaccurate about my writings, I will gladly accept criticism and be happy to discuss it and correct mistakes I have made. Otherwise I would appreciate it if you stopped. I don't suspect it will happen since I've made this request plenty of times both publicly and privately, but I suppose it doesn't hurt to make the request again. Otherwise I do hope the moderators eventually do take action pursuant of Guideline #2: https://www.thumpertalk.com/guidelines/ that you constantly violate.

 

Edited by MotoTribology
typo
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Moto T, 

The XR600r Honda manual for the linkage grease recommends  a 60% moly base. I cant find anyone that makes this high of a ratio, thus I've only used Honda grease. Any others you know of? Is this a matter of trying to get consumers to buy only Honda products? BTW : I do play in deep water crossings, thanks to Swampy's "Devils Creek" events!

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49 minutes ago, bork said:

Moto T, 

The XR600r Honda manual for the linkage grease recommends  a 60% moly base. I cant find anyone that makes this high of a ratio, thus I've only used Honda grease. Any others you know of? Is this a matter of trying to get consumers to buy only Honda products? BTW : I do play in deep water crossings, thanks to Swampy's "Devils Creek" events!

I can't recall percentages off the top of my head, but in my experience the 60% requirement is not totally necessary. A 60% moly grease is basically an assembly grease like I mentioned in the article above. So an assembly lubricant or an anti-seize grease from another company with high moly content should serve your purpose well even if it does have less moly than the 60% of the specific Honda product. I think they actually specified that it just had to have more than 40% moly. So I think the number is pretty flexible as long as the performance is there.

For the deep water exposure, just make sure it is waterproof and I would recommend at least NLGI 2 thickness to keep out the water.

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Hi Guys, the actual content of this discussion is very interesting, thanks!!  Shame we have to get side-tracked & get all nitpicky about He said/ She said...  Spoils it all...

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Great Article, I've been using Lithium Based grease ever since I used to drive an old Kombi years ago, when the CV's started to make noise out came the grease

I figured if it was good enough for my Kombi CV's it is good enough for the DRZ

..

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Is the drop point of a particular grease related to the NGLI grade or is that something that is always listed completely separately when it is listed at all?  

I have an air cooled bike with the oil (200°F+ at times) in the frame and I added a grease fitting to completely fill the annulus between the stem and frame neck to keep try to help keep moisture and dust out of the neck bearings (after reading your over-greasing information I'm wondering if that was a bad idea). 

Not knowing all I needed to know about grease, I looked for the neck bearing grease based solely on a high drop point so that the bearings wouldn't lose their lubrication and the grease wouldn't run down on my fender and such. 

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On 4/14/2017 at 8:43 PM, Hollerhead said:

Is the drop point of a particular grease related to the NGLI grade or is that something that is always listed completely separately when it is listed at all?  

I have an air cooled bike with the oil (200°F+ at times) in the frame and I added a grease fitting to completely fill the annulus between the stem and frame neck to keep try to help keep moisture and dust out of the neck bearings (after reading your over-greasing information I'm wondering if that was a bad idea). 

Not knowing all I needed to know about grease, I looked for the neck bearing grease based solely on a high drop point so that the bearings wouldn't lose their lubrication and the grease wouldn't run down on my fender and such. 

The dropping point varies on the type of grease, not necessarily the NLGI grade. Lithium, aluminum, calcium sulfonate, etc. all have different dropping points. Grease complexes have even higher dropping points than their simple counterparts. Clay based greases have the highest dropping point as far I can can remember, but usually a lithium or aluminum complex have dropping points above 500F.

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1 hour ago, bork said:

Mototribology, I was thinking of using this ceramic grease in steering head bearings for my air head frame? Would this be the perfect cure, to stop the run/melt out? (claiming good to 3000*F)

https://www.permatex.com/products/lubricants/specialty-lubricants-brakes/permatex-ceramic-extreme-brake-parts-lubricant-2/

To be honest with you, I don't really know. From the little information I can find on the product, it looks like it might be suitable for those bearings, and if it is, then I would expect it to hold up to any temperature you subject it to. However, I don't know if they put anything in there that is specific for brake calipers that would make it unsuitable for bearings. I would not expect it to be an issue, but the best bet is to ask Permatex to confirm it would be ok.

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5 hours ago, bork said:

Mototribology, I was thinking of using this ceramic grease in steering head bearings for my air head frame? Would this be the perfect cure, to stop the run/melt out? (claiming good to 3000*F)

https://www.permatex.com/products/lubricants/specialty-lubricants-brakes/permatex-ceramic-extreme-brake-parts-lubricant-2/

I'm running a 600°F drop point grease and haven't had any signs of it showing up on my fender yet.  It's been in there a good while now.  I'd say 3000° would definitely do what you wanted.

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On 4/10/2017 at 9:38 AM, MotoTribology said:

I've made a good habit of ignoring your lies and slander. However, since you are now accusing me of violating a copyright, I suppose I'd prefer readers of my content see that addressed rather than keep myself happy by avoiding responding to an internet troll.

You may want to at least read the articles when you, knowingly, falsely accuse someone of plagiarizing. The article you are referring to is significantly different than the one I wrote. There are certainly similar topics covered since they are both articles about the technical aspects of the basic concepts regarding lubricating grease, but the actual content in the articles is quite divergent from one another.

If you are referring to the consistency chart, those comparisons have been around for a long time. I believe they were first published here: 

Rudnick, Leslie R. (2005). Synthetics, Mineral Oils, and Bio-Based Lubricants: Chemistry and Technology (Chemical Industries). CRC. p. 468.

But as far as I know, industry people, such as myself, have been making those comparisons for decades as an easily understood way to describe grease thickness. So I would very much doubt that anyone has any rightful claim to those comparisons including myself.

I do hope you'll take the time to read content in the future with the open-mindedness to gain knowledge rather than automatically harassing the author with untrue claims. And if you see something truly inaccurate about my writings, I will gladly accept criticism and be happy to discuss it and correct mistakes I have made. Otherwise I would appreciate it if you stopped. I don't suspect it will happen since I've made this request plenty of times both publicly and privately, but I suppose it doesn't hurt to make the request again. Otherwise I do hope the moderators eventually do take action pursuant of Guideline #2: https://www.thumpertalk.com/guidelines/ that you constantly violate.

 

Is what I would like to see is you confessing that you are an Amzoil salesperson with very little experience when it comes to motorcycle maintenance. That way when you give advice to run API grades not specified for motorcycles, people will better understand your purpose for posting. :thumbsup:

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