In the case of automatic transmission fluid, it's designed to operate at around 170 degrees (according to a recent site that member MGD posted). It went on to say that for every 20 degrees above that, it shortens the life span of the fluid. If you tow on hilly terrain, you will see temps climb into the 200 range.

If you are going to change your Fluids anyway it doesn't matter how many miles you have on it.
I change my oil & rotate the Tires at the same time every three months, regardless of mile driven.
In the Ford Manual it said every 7500 miles.
After I purchased my New F150 it doesn't belong to Ford anymore. It belongs to me.

That's the proper attitude.....:thumbup:

So if yours says change after submersion then mine that is substanitally older probably needs it too

If you submerge the rear axle there is possibility it will now be contaminated with dirty water.
If the vent pipes and hoses are still intact you may be OK. Just depends on how deep you went.
If not, you need to either check and or replace the the lubricant as it is for the rear end and the rear wheel bearings.

is that this

https://cimg1.ibsrv.net/gimg/www.f15...422bdb051f.jpg

https://cimg3.ibsrv.net/gimg/www.f15...a252c40437.jpg

https://cimg5.ibsrv.net/gimg/www.f15...9ec2eab9a7.jpg

Bucko - As far as my transmission I believe I have the oil cooled tranny. I'm guessing that helps with temp, just not sure.

This morning I took pickup to dealer to flush the tranny. 60k is the manual recommendation, it's got 100k. I assumed they would drop the pan, clean the magnet, maybe replace filter, then put it back on and flush everything torgue and trans. They don't open the pan, what bothered me was they flushed it with all those good detergents yet the magnet still has metal fillings on it. Would this bother anyone else? I realize theoretically the magnet should hold them. Dealer said he checked the rear differential and said it was dirty, I have no reason not to believe him. I may change that myself. The tranny flush was total $195, any significant experience from anyone?

Synthetic oil can take a substantial amount of abuse before it breaks down, so for the rear end, as long as it is kept dry inside, it is pretty much sealed up other than the vent on top, so going a long time on original fluid is OK.

Transmission though, I find that hard to believe it can last that long. I know the fluids are much better today than they ever were, but 150K, That I just can't believe. Mine is always at 204* whether I am dead heading or towing. I will change mine out around 50K, that way if changing fluid causes something to give out( those who have had it happen know what I mean), it would still be under the powertrain warranty.

It would bother me, as I'd want the tranny's filter changed as well, and the only way to do that is to drop the pan.