For my tune-up, I was wondering which transmission fluid I should use. I have a high mileage engine, with a high mileage tranny, at 108,000 miles. No shift kit, no shifter, just stock. What should I use for my tranny? I was thinking of running synthetic for my engine, then I found out it takes the gunk out, and opens leaks and such, so I'm stickin with normal oil, like pennzoil, or valvoline. I don't want to remove any type of "gunk" (if tranny produces that, I dont know). So what transmission fluid is recommended? which ones should I stay away from?
Thanks!

 

I'm not really sure about the tranny fluid to use, but my guess would be go with Mobil 1 if you can afford it, I don't think trannies would have buildups like an engine, but get a second opinion on that one. Also if you don't have one, I'd recommend get a tranny cooler it will add life to your tranny.

 

Just use Dex III and you will be fine. For HD use I like Synthetic but if you aren't pushing it that hard it won't be of any benefit to you so save the money.

 

Well its better to be safe than sorry... what type of synthetic, what brand? Sure synthetic is good for high mileage tranny?

 

According to the oil tech people I have dealt with, the Amsoil dexron III is the best synthetic. At Trans-Go they use Mobil dexron III for all their non synthetic applications testing, I use Mobil dexron III also with good results. I have not seen good results on teardowns where Mobil One was used.

 

You better be sure the tranny fluid has been changed regularly up to this point. If it hasn't, even new fluid can cause everything inside to fall apart. I learned this lesson the hard way with a Buick I used to own. Changed the fluid one day, permanently parked the car the next. I imagine synthetic would do the job of liquidating the seals even better and faster.

If the previous owner doesn't have records of tranny fluid changes, call them and make sure they've done so. If they haven't in a long time, I'd take it to a transmission shop and ask them about it first. Maybe they can tell if it's been changed. If it hasn't, I'd just keep running the same fluid until you need to rebuild it. If you change it now, you'll have to rebuild it now. Be fore warned...

 

Whoa ****, Big Russ, now ya got me scared

 

Not trying to scare you, but that's what I've learned. People just DON'T change their tranny fluid like they should. My Buick had about 90,000 miles on it and the fluid hadn't been changed once to my knowledge. I was so pissed when I changed the fluid and it stopped working soon after. You'd think you're doing the right thing and staying on top of maintenance, but you end up screwing yourself.

I'd just take it to a tranny shop (a good one... make sure you talk to EVERYONE you know before going to a tranny shop because the wrong shop will make you squeal like a pig) and let them change the fluid and make sure they will take responsibility in writing such as a warranty. That way, if the seals fall apart and the clutches stop working, they'll have to fix it. If you can't go that route, I'd just drive it till it falls apart on it's own, since with that many miles it'll be due for a rebuild anyway.