|Originally posted by thesameguy:|
The heat byproduct from combustion is also related to output, not moving parts count. Xhp puts out about the same heat regardless of what made it. (Although, you *might* be able to show that a small motor will have superior volumetric efficiency and produce less waste than a big motor. Maybe. )
A smaller engine with fewer cylinders making the same power though, is probably doing so under boost and/or with higher compression. Greater cylinder pressure will amount to more heat/stress in the engine, and so such factors also matter.
Obviously, one should consider all the factors in play, and pick the best oil for the engine, based on them. Maybe that is a 15w50 oil, but it's unlikely unless it's a fully race prepped engine and you're going to be changing the oil very often. More than likely it will be a 5w30 oil, if it's an engine built with street driveability in mind.