10w-50 in a 05 yz450 ?


22 replies to this topic
  • FizzyMilk

Posted October 20, 2007 - 01:26 PM

#1

ordered some oil from rocky mtn. MC and the wrong oil was sent to me. just checking is a yamalube semi-syn blend 10w-50 is o.k. for a yz450 or should i sent it back? thanks

  • btray

Posted October 20, 2007 - 02:02 PM

#2

IN my opinion unless your in real cold weather that's the right oil to use...50 becomes 40 after it get's warm and and a little wear on it. I live in Texas and that is what I use...except I use Amsoil Synthetic.

  • grayracer513

Posted October 20, 2007 - 07:01 PM

#3

...50 becomes 40 after it get's warm ...

Not true. Larger number is the SAE viscosity at 212 degrees. 50 weight oil is only called for at ambient temperatures of 114 degrees or higher, and in generally it is a better practice to run the lightest oil capable of properly lubing the engine. The reason for this is that the lighter oil circulates more rapidly, getting more oil to the lube points faster, puts less load on the oil pump, and takes less power to move around. You could actually use a 30wt at ambient temps below 95, but in a ball bearing engine with a transmission, I prefer a 40. I do also run a 50 when the weather is consistently 95 or more.

...50 becomes 40 after it get's ... a little wear on it.

That is true of most engine oils when they get used as a transmission lube, and in fact, Yamalube may well turn into a 30 given enough time. But if the Amsoil you're using is MCV Synthetic Motorcycle Oil, it won't. There are a few others that won't shear down like that, too.

  • btray

Posted October 20, 2007 - 07:56 PM

#4

Like the thinner oil circulates better and less stress on the oil pump point...Isnt the 10 wt part suppose to circulate better while cold and the 50wt part suppose to help give a better separation between bearing parts and gears?

  • grayracer513

Posted October 20, 2007 - 09:56 PM

#5

Multi grade oils are labeled using two viscosity numbers. The first, the one with the 'W' next to it is the viscosity of the oil when cold (the W stands for "winter", BTW). While there is no particular official cold temperature established for this rating, 70 degrees F is generally used.

The second number is the viscosity at 212 F (100 C). This means that in the case of a 20w-50, the oil flows as well at 70 degrees as a straight 20 wt does, and at 212, it is no thinner that a straight 50 wt. This also means there is no functional difference between a 50 wt and a 20w-50 at that temperature, and that a 40 wt still flows better. Unless it's really freaking hot, you just don't need a 50.

These oils are created by starting with a light base oil (a 10 wt for a 10w-40), and modifying it with hydrocarbon polymers called Viscosity Index Improvers, which prevent the oil from thinning as much as it normally would when heated.

  • RM142

Posted October 20, 2007 - 11:17 PM

#6

What about oil breakdown with the long polymers in the 10w-50. I'm no oil expert but I was under the impression to stay away from oil with viscosity points greater than 25.I'm not sure how that applies here but I stay away from 10-40, 20-50 etc. synthetics may be a whole different thing, not sure.

  • Butta

Posted October 21, 2007 - 06:55 AM

#7

What about oil breakdown with the long polymers in the 10w-50. I'm no oil expert but I was under the impression to stay away from oil with viscosity points greater than 25.I'm not sure how that applies here but I stay away from 10-40, 20-50 etc. synthetics may be a whole different thing, not sure.


Grey has explained this quite proficiently before, and you are correct to have an interest in the "spread" so to speak. The greater the difference, the more reliance you are putting on the viscosity index improvers to maintain that higher grade property at 212F. He has posted a test showing several different lubes and their ability (or inability for some) to stay in grade through use. Amsoil MCV was the star of the test, and quite regrettably, the Yamalube "fell out of grade" much faster than I had expected.

Long story short, the "spread" is only important if you want to push the oil change intervals to the limit. If you change your oil often enough, you prevent the oil from being abused and falling out of grade.....OR, use the Amsoil MCV with confidence that when you drain it the properties are nearly the same as when you filled it.

Grey, how'd I do??

:crazy:

  • grayracer513

Posted October 21, 2007 - 07:51 AM

#8

Pretty good, Butta. You are quite correct that the viscosity range can give you and indication of how heavily an oil relies on VII additives. I would add that synthetic base oils generally have an inherently better viscosity index (less tendency to thin when heated) than petroleum oils before any VII's are added, so a 10w-40 synthetic will have fewer of them than the same grade of petro oil.

It is the transmission that breaks the polymers down so much faster in a YZF than in an engine-only application, not the heat, nor the high revs. But there are VII's available for use in multi-grade oils that were created for use in multi grade gear lubes, and will not break apart anywhere near as easily. These are more expensive, and because most engine oils are not made to be used as gear lubes, most engine oils don't use them. Some of the best motorcycle specific oils do, however, and that is why in the test referred to you saw the Amsoil and Mobil 1 M/C specific products, including the 10w-40's, show no loss of viscosity in the ASTM D-6278 shear test, even at 4 times the standard test length. Amsoil MCF and MCV are in fact actually graded as API GL-1 gear lubes.

Also, I run Amsoil MCF 10w-40 95% of the time, because as I said, a 50 is usually thicker than should be used.

But in answer to RM's point, if you are not going to step up to an oil that is proven (whether by lab tests or by your own used oil analysis) to retain its viscosity over time in a YZF, then the viscosity range is a good gauge of how fragile the oil may be, and in generally oils with a smaller range would be tougher.

  • RM142

Posted October 21, 2007 - 09:10 AM

#9

Grey has explained this quite proficiently before, and you are correct to have an interest in the "spread" so to speak. The greater the difference, the more reliance you are putting on the viscosity index improvers to maintain that higher grade property at 212F. He has posted a test showing several different lubes and their ability (or inability for some) to stay in grade through use. Amsoil MCV was the star of the test, and quite regrettably, the Yamalube "fell out of grade" much faster than I had expected.
Long story short, the "spread" is only important if you want to push the oil change intervals to the limit. If you change your oil often enough, you prevent the oil from being abused and falling out of grade.....OR, use the Amsoil MCV with confidence that when you drain it the properties are nearly the same as when you filled it.

Grey, how'd I do??

:crazy:



So without seeing the test results that gray posted and just referring to the statement about how fast yamalube broke down. One could say that this oil will work but maybe not a goood long term choice.And watch the change interval. In my vast quest for what oil to use in 07 450(note-did not start new thread):D a fellow TT'er mentioned some oils breaking down as fast as 35 min. in the YZ's. Thats pretty fast


gray, your posts are always packed full of info. I know when I do searches on issues on YZ's your name always pops up and has helped me a lot . Anyway thanks

  • yamaha racing 230

Posted October 21, 2007 - 03:44 PM

#10

wow thanks for the good info im glad ive been using amsoil

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  • dcoleh

Posted October 22, 2007 - 07:41 PM

#11

I would use it, I have used it before without any problems. If your worried, just change it after a few rides and use what you are comfortable with again. No big deal.

  • brandt509

Posted May 06, 2008 - 09:00 AM

#12

I was using yamalube 20w-40 in my 250f yamaha, found out they don't have that anymore, so I switched to yamalube semi-syn 10w-50. Is this a good choice for motocross apps? anyone recommend anything else. thought the yamalube was kinda pricey at $7.99/qt. for semi-syn......

  • grayracer513

Posted May 06, 2008 - 10:54 AM

#13

You can have Amsoil delivered to your door for about that much including the cost of your membership as a preferred customer, and it's a far better oil.

Read in this thread:

http://www.thumperta...470#post5426470

I wouldn't recommend Yamalube for anything.

  • brandt509

Posted May 06, 2008 - 11:28 AM

#14

GR, if you were me............
So....I have a 2004 YZ 250F, (engine/tranny oil is shared) live in Michigan (so usually ride in 50-90 degree weather) and race motocross.
What is the best oil for me? currently using yamalube semi-syn 10w-50, should I switch to Amsoil MCF 10w-40?

  • grayracer513

Posted May 06, 2008 - 11:39 AM

#15

I would, yes. You can also use MCV (same oil in 20w-50) if you prefer. I use MCF most of the year, running MCV for only late July through September, when it is quite often up over 90-95 all of the time.

  • brandt509

Posted May 06, 2008 - 11:45 AM

#16

Thank you, thank you, thank you GR, you rock. I really owe you one!!!!! ride on man!!!!

  • brandt509

Posted May 06, 2008 - 12:30 PM

#17

one more quick question; so......now that I am planning on using Amsoil MCF 10w-40, how often do you recommend changing the oil? I'm practicing/racing MX, so I'd say its under pretty harsh conditions......

  • grayracer513

Posted May 06, 2008 - 01:41 PM

#18

I change mine every third ride day, or sometimes sooner under severe conditions. I have gone 10 hours on an oil change, and the oil analysis was OK, but I don't recommend that. I'd say 4-6 hours of hard MX or desert stuff, or 6-8 of recreational makes more sense.

  • BASSic

Posted May 06, 2008 - 02:09 PM

#19

I've been wanting to try Amsoil MCV, but I've been changing my oil after about every 3-4 hours of riding since I replaced my clutch and I'm still seeing aluminum flakes trapped in the filter. I know a little metal is normal, but I'm still seeing more than what I consider to be normal.

For now I'll stick to el-cheapo Rotella 15-40 until my oil isn't so shiny and there's a 'normal' amount of aluminum flakes in my filter.

  • dejavudarrell

Posted May 06, 2008 - 04:13 PM

#20

Do you guys know that you can mix 10-40w with 20-50w of the same brand and have best of both worlds.:eek:





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