Thread: Td5 Disco 2 oil 15w40?

Originally Posted by sierrafery

IMO that's not 100% correct, i compared many data sheets and there are differencies, for example Penrite semi synth 5W40 has lower kinemaric viscosity at 100*C than the 10W40 and much higher viscosity index(so it's more stabile)

Most are around 14CST @100°C, +-.5CST, which is within batch tolerances.
I realise the SAE40 range goes from 12.5cSt to 16.something, but most SAE40 multigrades hover around 14 to 14.5cSt.

VI's didn't tell the entire story either, a 0 or 5W oil has a lot more VII's in it so will shear far faster in use.
There's quite a bit to the base oils and viscosity index improvers and how they work and what happens in use.
e.g. Mobil 1 0W-40 shears to a heavy SAE 30 oil well before an oil change is due, then start to thicken again with oxidation.

I didn't want to get into this level of detail and cloud the issue.

Originally Posted by sierrafery

IMO that's not 100% correct, i compared many data sheets and there are differencies, for example Penrite semi synth 5W40 has lower kinemaric viscosity at 100*C than the 10W40 and much higher viscosity index(so it's more stabile)

And the full syn mid-SAPS10W-40 HDEO has a far better NOACK number than the Diesel 5W-40 , so isn't near as volatile, which means less oil consumption in use.
Unfortunately Penrite don't publish NOACK numbers anymore.