Time for a slush change

[moroza]

My 525iT's slushbox was allegedly rebuilt "recently" as of a couple of years ago. I hate automatics, but this one works fine and I don't have the resources for even a stock 5-speed manual swap, let alone the 6-speed it deserves, so it's best to take care of it in the meantime. Were it original, I'd go "f--k not with", but I figure it hasn't been too long since its last change, so I bought two gaskets and a filter... now what about ATF? Any recommendations? All I've ever needed ATF for was steering fluid, and just went with whatever was cheap, but this is a fussier machine.

[shogun]

Is that the GM A4S270/310R ?
Black label on the pan or green label?

[ross1]

GM trans? Dexron
Don't forget to drop and clean the front O/D section oil pan. The gasket for it needs to be ordered separately, doesn't come with "kits"

[TheStigg]

ditto, Dexron. Spring for the extra bucks and get full synthetic i.e. Amsoil, Mobil 1, Redline, etc.

Application chart:

http://www.nmia.com/~dgnrg/SD92-113.pdf

[moroza]

I hadn't actually looked at the label, but assumed it's Dexron. I was asking for a product recommendation. Yes, I separately ordered the front gasket.

Is the likelihood of transmission seal leaks from switching to synthetic comparable to that with engines? I'd like to give it high-quality oil but damned if I have to replace the input seal shortly after.

[TheStigg]

Well, might just have to roll the dice on that one. I believe all current flavors of Dexron which are backwards compatible with the Dexron III, which was the original spec for your trans, will be at least a synthetic blend if not full synthetic. Depending on brand, some Dexron III's back in the day could be synthetic/synthetic blend. If the input seal is an occasional drip, then so be it. On the down side, a pronounced leaky front seal could be a bigger problem as in the 535i/735i ZF 4hp22, which usually leaks because the torque converter journal bearing walks forward and pushes the seal out. Let's hope you don't have to deal with such a scenario in the dead of winter. On the upside, it's an easy fix once the trans is out.