Originally Posted by bbywu

Remind me not to purchase a car from you.

Originally Posted by 2011PorscheCaye

so i'm thinking about how temperature makes a difference for performance of engine oil. the purpose of engine oil is primarily to lubricate the moving parts within an engine. if that being the primary function (with a few other things as well), how does temperature affect engine oil?

i think we all know that as temperature rises, engine oil becomes less viscous. I'm sure that there's some optimal viscosity the engine oil is at to properly lubricate the engine. that being said, there must also be an optimal temperature.

so i did some quick research, and it looks like the relationship between temperature and motor oil is logarithmic. Once you hit 50C (122F), the change in viscosity is almost nothing all the way up to 200C (212F). Check out this link: http://www.widman.biz/English/Calculators/Graph.html

As a note... I took my car out for a drive earlier and saw that right around when my coolant hits 200F my oil temperature is around 120F. Granted I assume the oil temp will take longer to heat up if sitting at idle, but if driving normally by the time your coolant hits halfway i think your engine oil is ready to go.