Mobil Truck & SUV Honda Valkyrie

[Blake Sobiloff]

Extreme-Duty, the shear rate due to engine RPMs/operation and the oxidative thickening rate tend to balance one another out in most automotive applications. They key differences in a motorcycle application are 1) potentially much higher RPMs, and 2) vastly greater shearing action from transmission gears. In short, motorcycles shear the heck outta the oil long before any oxidative thickening can occur and rescue the viscosity.

I fear that I sound like a broken record, but there are really only two ways to avoid running oil that is grossly out of viscosity spec: 1) Change the oil frequently (every 1,500 miles or so), or 2) Use an ester-based oil and monitor the viscosity performance via UOAs.

Terry has also told me that LC20 can help reduce the amount of viscosity loss, so that may be worth investigating as well. (As if you really needed another reason to use LC20!)

 

[RevRider]

As a side note, when I picked up my bike from service, I brought home the air filter, oem, at 12,000 it was thrashed with dirt. This was the recommended change interval. I noticed my mpg had dropped from about 32-33 to barely 30.

Probably a better change interval is about 6000...

RevRider

 

[Extreme-Duty]

Black Sobiloff,

Yes, ester-based oils weights seem to shear less PAO-based oils. And yes, I know that MC's shear the oil much faster than other automotive engines. Excuse my long post, maybe it isn’t that useful for this discussion, but it is about my short motorcycle experience. Feel free to ignore it, the more important part is my question.

Before i got my car I had a tiny Suzuki Marauder GZ 125. I brought it with about 12500 km on it, and the Suzuki dealer gave me a Castrol 20w-40 MC-oil (dino) for my first OC. The second time I needed an OC, the same dealer gave me a PCEO (SAE 15w-40, API SJ/CF, ACEA A2/B2). I asked him: "Why a car-oil?". He said: "It's good enough for your MC". He charged about 8 usd/qt. (Oil is very expensive at German stealerships). However, I asked him why he did not want me to use the XHVI-based Shell Advance VSX 10w-40 he had on his shelf at 12 usd/qt. It is too expensive for your application, he replied. Then I suggested to use a synthetic PCEO instead of, which he did not like, because the FM's makes them too slippery for the clutch. I didn't know much about oil (nothing) a that time, so I brought 2 litres (enough for 2 OC's) of the dino car-crap.

Within the next 4000 km's, the engine got more and more noisy, while it smelled of burned oil. The oil turned black as cole, so I knew it was time to do some research on oil! The second fill of PCEO was then drained after 800 km and I replaced it with fully synthetic ELF Moto 4 XT 10w-50 at 10 usd/qt. from an honest Yamaha dealer. Again, it was drained after 800 km, because I thought it was a good idea to reduce the first OCI on synthetic. The oil looked relatively new. From then on, I changed it every 3500 - 4000 km. After 3500 km, the synthetic MC-oil looked the same as the PCEO did after 800 km. Conclusion: High quality motorcycle-specific oils seem to handle motorcycle conditions better than low-cost PCEOs.

Now the important part:

OK, A petroleum-based SJ/CF oil can't be compared with a Group 2 CI-4+/SL HDEO. My question is why we see such an extreme loss in viscosity with most PAO-synthetics (both 5w-40 and 10w-40 weights) within 500 – 1000 miles. In oppositon to the synthetics (which are considered to be superior, using less VII than a 15w-40 dino oil), the HDEOs seem to stay in grade. Can all this be attributed to an obviously higher shear-stability of a HDEO, or is there something else involved? For me it is difficult to imagine that a group II 15w-40 is more shear-stable than a PAO-based 10w-40. Please help me out of this. Thanks.

BTW, I need learn about LC20, sounds interesting, I have to browse the additive section.

Best regards,

ED.

 

[doubleshockpower]

When Honda for example recommends a 10w-40 don't they anticipate that some sheering will occur? and really they do understand that a 40w sheered down to 30w is what they are comfortable with all along. These people have everything down very well so I'd doubt they've overlooked the sheering issue.

 

[wileyE]

good point, read elsewhere that honda and most the japanese do their durability testing with automotive 30w's. Some models of hondas even recommend 30w.

As far as viscosity vs. operating rpms I've always understood that low rpm highly loaded engines require the thicker stuff (think ma and pa on their touring bike pulling trailer). The higher rpm motors (usually less loaded) favor thinner oils (think 250cc mx bike). Put thick oil in a highspeed blender and no doubt it will break down fast. May as well started with a thinner oil and avoided some of the foaming and aireation that can possibly starve some parts of the engine until it thins down. At wfo some of the 600cc sportbikes on a dyno you can actually hear a starving cyclic sound as the oil cycles from the sump to the head and back. Lower viscosity stops it.

[ April 30, 2006, 06:32 PM: Message edited by: wileyE ]

 

[GMorg]

RevRider,

Given that your UOA shows wear below average, why do you even care that the oil sheared. It seems to be preventing wear.

 

[RevRider]

GMorg,

In the truest sense, I believe you are right, wear is the issue to be concerned about, and I am pleased M1 protected well.

I am presently trying Shell Rotella, 5w/40 to compare to the M1 Truck & SUV...

With M1 Truck & SUV now being reformulated into the 5/30 and the turbo diesel 5/40, I will probably use the Rotella or the Delvac 1. I also have 4 quarts of the M1 motorcycle specific on the shelf...

RevRider