Originally Posted by shertex

Countless forum members have expressed perplexity when attempting to measure ATF level (including me, at one point). They are told to measure it hot, at operating temperature....say after a good run on the highway for 30 minutes. But then they encounter all sorts of uncertainties, basically revolving around the question of whether it was really hot enough when measured. Can be very frustrating.

It seems to me that the reason the FSM provides the "hot" method is that most people, and most mechanics, will be measuring the level on a warm/hot engine: during a trip, a visit to the mechanic, etc... So it makes sense.

But for DYI'er, there's absolutely no need for this method. The FSM specifies ANOTHER method: measuring at 20-30C (in other words, ambient temp on most days). See p. 1 and 3 here: http://www.w124performance.com/service/w124CD1/Program/Maintenance/My81/2710.pdf

So as long as the engine is cold and it's 68-86F outside, I know I can get an accurate reading every time.

When it's colder, I don't know if the measurement would be different since I don't know if there's significant thermal contraction at lower temperatures. Anyone know?