Transmission Fluid

Read that transmission fluid expands as it gets to running temperature.
Can anyone confirm this is correct? Thanks, Woodcutter

 

Well fluid molecules when warmed have more kinetic energy so yes, it expands but not a whole lot. Curious as to why you are asking?

 

Yes, thats why most transmission dipsticks have a cold range and a hot range

 

Yep, some ATF types (like WS) expand more than others. That's why in newer gens, Toyota has a more complicated procedure for indicating correct temperature range for fluid level checks.

 

Well, since it expands then the actual fluid level will be higher than indicated then if the fluid if read when cold. So to insure you do not over service always check the transmission fluid level at running temperature.

 

Have you pulled the dipstick and looked at the level marks yet?