I have heard it suggested to get the atf fluid changed every 30k miles. However I live in the coachella valley where it's over 100 for much of the year. Will the heat have that much effect on it seeing that the fluid gets heated to higher temperatures under use?

 

I would replace every 10-20k miles.

 

Yes, heat is what kills transmissions. I would change the fluid every 20K miles.

 

When i had my TL i did the transmission fluid every 3rd oil change since i was under the car anyways

 

I did the original 3 X 3 at 50K miles, and since then, I do a 1 X 3 every other oil change, so roughly every 15K miles.

 

Does sitting in the direct sunlight with an ambient temperature over 110 all day add to the breakdown of the fluid?

 

Where are you that it gets that hot...Phoenix? Anyway, I wouldn't think that ambient temp would have that much to do with fluid degradation.

 

Palm desert

 

yes heat does degrade the fluid quicker than normal, at this point I would replace every other oil change.

 

Yes, heat will increase the service intervals but that depends on how long your trips are and how fast you drive. If you only commute half hour or less it probably not an issue. But if you're in stop in go traffic for an hour, that is severe use and a real concern or doing 100+ mph a lot, then again, severe use. Increase in service intervals is required.

The 30k you're referencing is probably talking about the 3x3 not just a single 1x3.

The 3x3 is roughly about 80% of atf change on paper. The more the mileages accumulate inbetween each 1x3, the lower the percentage.

If your car does not have a trans cooler, you might want to install one.

.02

 

I'd personally do a drain and fill every 15k. That interval worked for me since I replaced my engine oil every 5k.

 

Every 15K or every other oil change is what I tell all my friends and family. $300-400 of fluid over 200K miles is better than $3000 for a new trans.