Do single weight oils have a place?

[Cujet]

Single viscosity oils often have higher HTHS ratings. They may be a smart choice when extremely high temperatures are expected. They also may be less prone to shear, such as when used in a motorcycle with a shared transmission.

We use single viscosity oils in piston aircraft engines with good results.

 

[oilpsi2high]

My boat calls for SAE 30. Volvo Penta 5.0 GXi.

 

[expat]

Originally Posted by hatt
Originally Posted by expat
So assuming Jay Leno is being advised by someone knowledgeable, and expence is no real object, has anybody any idea why a 50 wt would be spec'd?

I think think the engine holds about 8 gallons!

Comparing vintage piston aircraft engines to modern econobox car engines is apples and donuts. Just what oil do you think he should use? TGMO 0w-20?



No! I assume the engine might require a 50 weight oil when hot.

But why would you want to subject it to a 50 weight oil when cold? (Yes, even California is cold when it comes to engine oil)

So considering the engine is low stressed and has a large oil capacity, why not good a 20W-50?