Engine/Transmission (1998.5 - 2002) Trans fluid breakdown

[Hobart]

At what temps will the trany fluid begin to break down? I went up to 300 a couple of times for a few minutes; and it is not unusual to go to 250 on a steep hill in hot weather. This is the output side ; the pan temp is always much lower. Open road temps are in the 150 range. (I've got the double deep pan)

 

[BWagnaar]

I believe 240 deg is when it starts to breakdown. I can't remeber how/where I got that fact but I'm pretty sure that is correct.

 

[Hobart]

I wonder if amsoil fluid is worth the extra cost? And how many miles I should run before a change considering I carry a cabover full time?

 

[rotohead]

I've been told to change every 12-15K miles if you tow. At that interval it's hard to justify synthetic IMO. About 250 deg and above will shorten fluid life. Best to take that temp in the return line to pan, not in the pan itself. The older the transmission gets the shorter the fluid change interval should get.
Chuck

 

[Hobart]

The high temp reading was in the return line. I'd say it was in the 275 to 300 range for about 10 minutes. SO I guess a change is in order. Valvoline atf+4 says synthetic. Less than $4 a quart at my local NAPA!

 

[cerberusiam]

The high temp reading was in the return line. I'd say it was in the 275 to 300 range for about 10 minutes. SO I guess a change is in order. Valvoline atf+4 says synthetic. Less than $4 a quart at my local NAPA!

ATF+4 is rated to 320 degrees peak temps for a short time. If you are seeing temps over 260 frequent then changing it out very 15-20k is reccomended.