High Compression vs.Low Compression engines

Not open for further replies.
Sep 28, 2002
Does a higher compression engine benefit more from an oil that has a higher HT/HS (high temperature/high shear) rating, vs. a lower compression engine? Street engines, not racers. Does the higher compression cause more of a shearing effect on the oil?
I don't exactly know about shearing itself, but higher compression engines put more stress on the rod bearings, and have higher combustion chamber temps for the most part. I would expect these two features to put more stress on an oil and engine, thus I would prefer an oil with higher capabilities in those departments to improve cooling and have stronger viscosity in the bearings.
Higher compression engines generally have greater ring tension which places higher radial loads on the cylinder wall, creating more shear on the oil.
My engine is 11.5-1 and I'm using Castrol 5w30 for the first few thousand break-in miles. I will post the oil analysis after I change the oil for the 2nd time. Then I am going to switch to synthetic for 2 oil changes, sampling the 2nd change to determine which oil shows better results. Should be interesting... Jason Edit for typo [ January 16, 2003, 01:31 PM: Message edited by: DABEAR95 ]
Not open for further replies.