10W40 motorcycle oil HTHS

[mechanicx]

Does anyone know the HTHS rating of 10W40 motorcycle oil. It seems that the API Service rating would allow for HTHS to be as low as 2.9 for a 10W40 as opposed to a 15W40 which is over 3.7. 2.9 seems kind of low and I don't know that they are in reality, but that's what I'm trying to figure out.

Does anyone know the HTHS rating for Valvoline or Castrol 10W40 mineral oil or synthetic?

 

[dparm]

I would be surprised if it were under 3.5. Heck, Motul 300V 10w40 (albeit a race oil) is 4.19.

 

[Quattro Pete]

Here are HTHS figures for some motorcycle 10w-40 oils:

 

[mechanicx]

Wow where did you get all that info? I assume those are all 10W40's? I haven't seen some of those brands around. They appear to be mostly synthetic, but I imagine the conventionals would have at least over 3.5 cP HTHS. I wonder if the Valvoline is synthetic or their conv? It's has really really high HTHS. With the way bikes tend to shear oil it seems you could use all you can get.

 

[AVB]

I think Amsoil published that, not sure if it is up to date. I remember seeing that several years ago.

 

[mechanicx]

Yeah I'm mostly interested in valvoline and also castrol's mineral oil HTHS rather than the synthetic "racing" versions. The castrol which I think is synthetic HTHS is not too impressive and I thought it was good stuff.

 

[Quattro Pete]

Originally Posted By: mechanicx
I wonder if the Valvoline is synthetic or their conv?

The Valvoline 10w-40 oil they tested is mineral.

Here's a link to the full Amsoil study from which this chart came.

 

[CATERHAM]

Originally Posted By: mechanicx
The castrol which I think is synthetic HTHS is not too impressive and I thought it was good stuff.

The HTHSV of any oil is not good or bad. HTHSV is simply the true measure of how thick or thin the virgin oil will be in an operating IC engine.
Most normally ridden street bikes tend to run cool oil temp's, consiquently a lighter oil (lower HTHSV) is most suitable. In fact a 4T 5w30 is usually best. Short of installing an oil temp' gauge or better still an oil pressure gauge so you don't have to guess about how heavy an oil you actually need, experienced riders can get a pretty good indication from the shift quality of their bike. Since most bike's gearbox shares the engine oil, if the oil is getting too light you'll know it with very notchy gear changes when the engine oil is hot.

 

[mechanicx]

Baased on recommendations my bike, like most, recommends 10W40 and xW50 above 104 F. 10W30 is a grade that can be used below 86 F but it can regularly get above that temperature here. It's Hard to find motorcycle oil that is 10W30 and I'd want more HTHS than 2.9.

With the way it runs hard, with carbs, high output per L, shearing from gearbox, and high RPMs, I'd want at least 3.7 HTHS or higher. Maybe it isn't needed but I can't see how it hurts.

 

[MolaKule]

Amsoil says about 4.5:

http://www.amsoil.com/storefront/mcf.aspx


6.1 for this puppy:

http://www.amsoil.com/storefront/mcv.aspx

 

[mechanicx]

Nice although that 6.1 just might be overkill for my bike, temperatures and riding

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