Those of us who are mechanically sympathetical know that you don't rev an engine hard when it is cold. The oil is cold and too viscous to flow to those parts of the engine at the rate required to provide proper lubrication (metal-on-metal, ). Of course there is an oil pressure factor in the first few seconds on starting an engine, but I trust no-one is stupid enough to rev an engine directly on starting it.

My question is, in the absence of an oil temperature gauge, how does one know when the oil gets to a working temperature where it can provide full protection ? I know that the water will reach it's operating temperature before the oil temperature, but can the water temperataure be used as some sort of indicator ?

What rules of thumb do you use ?

 

my totally non-technical method is 20 mins. i use this based on what i remember from some tv advert for shell/esso (something like that) saying oil takes 20 mins to get around the engine. its probably wrong tho but i keep revs below 4k and keep off boost until this point. sometimes leave it less if the cars only been off for an hour or less.