88 4+3 trans fluid change

[Paul G]

I have the fluid drained out of the gear box and the overdrive.
What are the best fluids to put back in? Maybe synthetic?
Do the lines to the radiator need to be flushed out?

This is the first time I am doing any work to the trans. I have a leak at the shifter shafts on the side case of the gearbox. Any one know where I can get replacement seals for this?

Thanks,
Paul G.

 

[Ken]

Just looking for posts with no replies yet.

Sorry no one responded yet Paul. I assume you got an answer somewhere else, but the fluid to use is ATF. It's a matter of personal preference as to whether you use synthetic or not. Synthetic lubricants will withstand higher temperatures, which is the worst enemy of an automatic transmission, and the overdrive unit works in much the same way as an automatic.

The lines should drain much of what is contained within when you pull the transmission pan.

I either read somewhere, or someone told me, that because there are two types of fluid (gear lube in the four speed & ATF in the o/d unit) separated by a seal that is prone to failure, that they used ATF in the gearbox as well as the o/d unit. That way if the seal failed, it wouldn't affect the overdrive operation. The four speed (Borg-Warner Super T-10) was a bit noisy with the ATF I guess. :L

Good luck with your transmission.

 

[rrubel]

Wait - ATF *instead* of gear lube? Gear lube is like 90w oil and ATF is like 5w oil. Isn't that going to drastically cut the life of your transmission?

BTW - Paul, I too have a small leak at the side of the shifter where the shafts come out of the box. Any luck fixing yours?
[RICHR]