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crush6742

oil change recommendations

21 posts in this topic

Thumper engines have little slipper pistons with few rings, so they tolerate a lot of compression blow-by. That means that the oil gets diluted out by fuel rather quickly. This makes frequent oil changes a must! This isn't your dad's old XR.....

Better to often rather than to little! I never go more than around 5 hours, unless I am on an all day ride.

Read about it: http://www.belray.com/consumer/techinfo.fsp (Click on "Thumper Revolution" to the right, to open pdf.)

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Actually, the piston in a YZ450 has the same number of rings as a late XR650; 2 compression, and one triplex oil ring, the standard throughout the automobile industry. The 650 also uses a slipper style piston, as do Corvettes and Camaros from 1998 onward.

Change your oil AND filter every 3 ride days or more often. That should be under 8-9 for almost everyone in terms of engine run time. Be sure you use an oil capable of that. If you buy bulk automotive oils, change every ride, or every other.

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I don't think so. There is no mention of it being synthetic. It says performance all purpose four stroke on the bottle. This is what the dealer gave me to use; around $6 a quart.

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At $6/qt, I wouldn't expect much from it. Plan to use their better stuff next time. I personally use Amsoil MCF (10w-40), but there are a number of good oils available. Mobil 1 Racing 4T, some of the Motorex and Motul line up, etc.

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At 60 degrees or higher the manual says Yamalube 4 (20W-40) and if the temp was below that then Yamalube 4 (10W-30). I personally run Amsoil 20W-50 all season long.

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What is the difference between the 20w-40 and the 10w-40. The manual does mention this but it seperates it out into two categories: US and Can, and Non US and CAN. Not sure why they did this. If you look at the temperature table the 10w-40 covers a range of between 50 and 110 degrees, I think. I don't have the manual with me right now.

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The only difference in the US/non-US listing is that in the US one, they recommend a specific brand. Why they don't do that elsewhere is unknown to me (and frankly, I don't worry about it).

Look again at the chart in the manual. 5w, 10w, 15w, and 20w-40 oils all cover to the same maximum of 114 ℉. The difference is only in the minimum temperature covered.

Multi-grade oils are made by starting with the lighter listed base oil and adding long chain polymer additives, called Viscosity Index Improvers, or VII's, to them to prevent them from thinning out as they heat up. So, with a 10w-40, what you end up with is an oil that flows as easily as a 10w at 70 ℉, but at 200 ℉, is still as thick as a normal 40 weight would be at the same temperature.

The trouble with these oils in YZF's and other engines that share engine oil with their transmissions is that the shear forces applied by the gearbox can easily shred the polymer additives, leaving you with 10w-25 instead of a 10w-40 in a shockingly short time. Engine oils that were not specifically formulated to be used as gear lubes (which is almost all automotive engine oils) generally don't use the tougher polymers found in multi-grade gear lubes simply because they cost more, and engines don't need them.

A 10w-40 oil will be more dependent on VII's to stay thick than a 20w-40 of the same chemical base would, and so would be more subject to viscosity loss through shear. Likewise, full synthetic oils generally have a higher natural viscosity index then petroleum products do, and so a synthetic 10w-40 needs fewer VII's than a petroleum 10w-40 does.

If you have no other info to go on, you can guess that a full synthetic would retain it's viscosity longer than a petro oil, and that a 20w-40 would last longer than a 10w-40. But it's better to know by using published lab tests or testing a used sample from your own bike.

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Thanks for the follow up Gray. based on your recommendation, I will change the Yamalube 10w-40 with the amsoil 10w-40.

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If you decide on the Amsoil product, be sure you have the right one. The only two I recommend are their Advanced Synthetic Motorcycle Oils (MCF or MCV)

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Certainly you meant 30 miles?

Depends how he rides. At 40 mph, 300 miles would take 7.5 hours. A little on the long side, but with a truly suitable oil, it's not so outrageous.

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Depends how he rides. At 40 mph, 300 miles would take 7.5 hours. A little on the long side, but with a truly suitable oil, it's not so outrageous.

I guess when you break it down it doesn't sound crazy. At first glance it seemed way too long.

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i use mobile1 synthetic 4 stroke in a 04yz450 as does my next door neighbor in an 01 yz426. we have both found the oil looks good when coming out in the 6-7 hour range but starts to get dark by 8-9 hours.

as the bike only holds just over a quart, i just change it every other ride or so to keep it nice and fresh. for the last 15 years, I have always changed my oil sooner rather than later and have never had a motor fail. i see it as cheap insurance.

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I've used straight Kenda 10w-40 and use Lucas oil additive as per instructions on the bottle for years. Use it in my drag bikes, race bikes, and recreational bikes. Engines have never looked better. Highly recommended. I know of a ton of people doing the same including some seriously high hp machines and top racers. Cheap and effective. What more do you want? A lot of the oil out there is over rated and over priced in my opinion.

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