Transitioning to synthetic ATF questions

98 V-6 (supercharged) Auto, about 163 K on the clock and running good and strong. Planning to drive it into the ground (I live in Pacific NW so not too much salt on the roads, and I wash the underside regularly in the winter, so the frame is good) Very little/light off-roading. Tranny seems strong as well. I have an aftermarket tranny temp gauge, and cooler (Hayden 675) and since the move to 33's (from the original 31 x 10.5 LT's) the tranny runs hotter in non-freeway driving. Once I can hit ~50 or so and the TC locks temps drop pretty quickly, but I can't hit 50 on the surface streets. Plus, I go up a pretty substantial hill at 30-35 to get to my place, and the tranny can touch 190* or so depending on the weather. I do shift out of OD when going up longer freeway hills, and that helps.

I just had a 4-quart trans fluid drain-fill done at the dealer, so I'm set for a time. I'd like to start doing a drain 2 qt/fill 2 qt tranny fluid exchange with every oil change (5-6K mile intervals) to keep things fresh, and as long as I'm going to be doing that, I want to consider transitioning to a synthetic fluid (Royal Purple or Mobil 1). I admit I'm leaning toward the M1 option as that's the oil I use and I've had good results with it. My owners manual states the drain/fill is 2 quarts, so the dealer must have done it (?) twice? Either that or they charged me for 2 unused quarts as the invoice is for 4 quarts, and I didn't think about the difference between that and what the owners manual says...

My questions are, the RP website states their fluid is compatible with conventional fluids (and I know motor oils come in synthetic/conventional blends): "Max ATF is fully compatible and can be mixed with other automatic transmission fluids; however, for the best results, drain or flush the current oil and then fill with Max ATF synthetic automatic transmission fluid." Can I assume the M1 fluid is compatible as well? Has anyone done this (run a 'blend') of conventional and synthetic fluid? If so, any good/bad results?

Next question: Am I risking any harm to the tranny by running a blend? Obviously, the more times I do this, the closer I'll get to a 100% synthetic state, but it's going to be about a 3 year or so process to get there (I don't drive a lot so I'm only changing oil every 8-10 months). Given the total tranny capacity is ~10 qts I'm looking at 5+ changes to get 80%+ synthetic in there (because each time I drain it I lose come of the current synthetic in the 'blend').

I'm hesitant with that many miles on it to just make a full swap to syn at one shot, I'd prefer a gradual transition (unless you all talk me out of it).

Thanks for the help and advice!

 

Bump

 

It's hard to say. Have you ever checked the fluid? Are you the original owner? Most people with superchargers do valve body upgrades along with bigger tranny coolers. If the fluid is brown color it's pretty much toast. Dont bother changing it. I change mine every 30 - 60K with Amsoil Universal Atf.

 

Ill be doing the method listed on the page below vvv

https://www.tacomaworld.com/threads/silverghost-rises.360448/page-7

I recently did the drain and refill but I'm gonna do it about a quart or two at a time until it starts coming out with the new fluid

*FWIW when I drained mine I got about 3.5 qts out of mine so the dealer probably didn't screw you on that