[TheOtherLeft]

I'm about to change my fluid in my auto transmission in my J20A Grand Vit.

Is it worth shelling out the extra coin for synthetic fluids - Castrol Transmax Z, as opposed to the mineral TQ-Dexron 3.

I know the transmissions are known to run hot. Even just putting your hand on the transmission tunnel when driving and it feels warm. Would using synthetic fluid be of any benefit given the higher cost compared to mineral oil? Castrol quote a 20 deg difference in temperature between synthetic and mineral when under high loads.

I have thought about a transmission cooler but using synthetic might be a cheaper option???

[atari4x4]

I would install a transmission cooler no matter what, the extra volume alone would be beneficial + the added bonus of cooling the fluid at the same time.

[ajsr]

Its supposed to be good shit, but if your worried you should fit a cooler as well.
Just because the fluid can take 20 deg more doesn't mean the rest of the box is going to like the extra temps.
personally I think ALL autos shoud have an extra cooler fitted.

[royce]

When you change the oil in an auto you are lucky to be swapping out 50% of the oil so its not worth it unless you strip and drain the box and convertor

i'd go a big cooler

[SuziBlu]

Royce, are you sure, I was under the belief that when done properly you got over 905.

[BJPK]

SuziBlu wrote:

Royce, are you sure, I was under the belief that when done properly you got over 905.

the only way to get it all is if you flush it with a machine. you dont get much more than half if you just drain it through the pan.

[SuziBlu]

I have never flushed or changed oil in an auto, always get a mechanic to do it, and a filter.

Doing it yourself, unless you have flushing capacity is false economy IMO, an I do most everything myself.