Sequence IVA wear test vs oil viscosity

[friendly_jacek]

Are all viscosities tested on the same/similar engine in the Sequence IVA wear test?
If so, is it harder for 0W20 oils to pass it (less than 90 um) compared to heavier oils?

 

[Shannow]

If you would believe the popular opinion that passes as fact on the board, a 0W-20 would get to the top end quickly and start protecting...therefore should protect better than anything available.

I believe, however, that as top end is more boundary/mixed, that additives play a stronger role in what goes on up top, and that Sequence IV is designed to run them on the limit of activation.

Viscosity shouldn't matter to any degree in that.

 

[camelCase]

It's a mix of boundary/mixed and hydrodynamic.

All of the shaft supporting bearings should be in full hydrodynamic lubrication while the cams, piston/rings/cylinder, and other reciprocating parts will be in that boundary/mixed.

You are correct in that the anti-wear, and similar, additives really get to work in boundary/mixed lubrication. However, the anti-oxidants, and similar, are needed no matter what, typically.

 

[weasley]

The Seq IVA is run on the same engine regardless of the oil being tested. It is a well-defined test using a Nissan KA24E engine. Whilst bearing and piston protection are required to make sure the engine can run to the end of the (100 hour) test, they are not rated - only the cam lobes are measured for wear.

 

[vinu_neuro]

You can get down to around 2.1 cst before passing the 90um limit becomes an issue. As shannow said the additive package matters most for Sequence IVA. You can get lower wear in IVA with a 20wt than a 30wt.