Amsoil 10W40, 150 KM/95 miles Suzuki SV650

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Jun 9, 2003
Ontario, Canada
My son has started racing motorcycles and we are experimenting with oil change intervals. This UOA was after 2 race weekends.
This is Amsoil 10W40 motorcycle syn oil
Analyzed by Wear Check, Ontario, Canada

Fuel ...... Water...... Sulfation..165
Visc@100 Deg C...11.8

We changed the oil after this analysis but we are looking for some guidance from the forum. We are primarily worried about viscosity loss due to shear in transmission.
Is this oil still OK for use?
Is viscocity still OK?
Or should we change after every race?
Besides viscosity - what other critical parameters should we watch for?
wulimaster: This is the older Amsoil oil
TooSlick: The fuel is normal high octane pump gas. The bike is fuel injected. I would like to use some labs in the US-like Butler- but cross border shipping is a pain and also expensive.

Do you have any idea how much viscosity we have might have lost compared to virgin oil if it is now at 11.8?
Looks like I may have found the answer to my own question!!! I found the specs for the old "AMF" Amsoil 10W40 and viscosity was 14.7. Thus we have lost about 20% - which seems significant.
Looks like we had better change it after every race weekend?
I have an SV650S and other SV riders will also tell you to go with shell rotella T hdeo for the bike and just change it every race for how cheap it is. I know a few people that have put over 100k miles on their sv with shell rotella t and never had any problems or ever had to replace a clutch.
I disagree with changing every race. The oil has thinned a bit, but it's still protecting. All the other numbers are low. Heck you would probably make better times with the lower viscosity.

I have a guy racing an SV as well. I've often wondered if I should recommend that he uses HDD 5w30 to get the most power.

I would be interested to see how the new stuff works out though.
How many hours on this sample?


How do you know that 90% of this wear didn't occur AFTER the oil sheared down by 15%-20%?
You certainly can't corrolate the rate of shearing with the wear rate, since the only analysis was AFTER the second race had been completed.

Let's assume the baseline, HT/HS viscosity has also degraded by 20%; down to say 3.4 Cp. If you ran a third race using this sheared out, SAE 10w-40, how would the engine hold up?

I'd suggest testing after just one race and see how the #'s come out. That will tell you if there is anything to be gained by more frequent service.
The viscosity loss is normal, and motorcycle manufacturers spec thicker oils to accomodate the shearing.

WearCheck is an excellent lab. How lucky for you that they are in your home town.

The numbers to watch for--above all else--is the wear numbers. In this case, not many people here have experience with motorcycle UOAs with only 95 miles. I think it would be cheaper, and more instructive in a racing application, to cut open the oil filter after a couple of races and inspect it, rather than send oil off for analysis.
What kind of fuel are you using? It looks like you're getting fuel dilution.

I also don't understand Na @ 63 ppm?, unless this is the new MC lube. In that case, I'd say it's part of the additive chemistry, based on past experience.

I'd use another lab like Butler Labs and these allowable limits:

1) viscosity loss < 20%
2) fuel dilution, < 2.0%
3) silicon < 15 ppm

Fuel dilution > 1.0% will drive the viscosity loss at least as much as any shearing.

A simple solution would be to run the 20w-50 expect significant fuel dilution. That would allow you go go longer between changes, since you're no where close to the TBN or silicon limits.
The new Amsoil 10w-40/20w-50 MC oils will not shear at all. Shear loss after 120 cycles on the industry standard, "Kurt Orbahn" (some bright German chemist, no doubt
), shear test was on the order of 0.5%.

Use the new Amsoil 10w-40 and this problem goes away ....

I cut open the filter (K&N-138) and everything looks OK. No debris visible. Looks like the engine is still healthy!!

TooSlick: Thanks for the advice. Will get the newer Amsoil when this case is gone.The specs for it look a lot better.

The Amsoil MC oil from several years back:

14.0 Cst @ 100C, HT/HS of 3.93 Cp @ 150C

The new Amsoil 10w-40/MC oil:

13.9 Cst @ 100C, HT/HS of 4.52 Cp @ 150C.

From the ratio of the vis @ 100C to the HT/HS vis @ 150C, I can tell the new stuff is much more shear stable, since it's much less "squeezable" in the tapered bearing simulator. Hence it has little or no polymeric thickener....

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