Hey guys, I have a '85 gsl-se and its time to change the trans/diff oil. I was just wondering what viscosity and brand work well. I've started hearing a grinding sound coming from the back of the car only on sharp left turns. The diff has a leak, maybe the sounds coming from diff because of lack of lubrication? Thanks, luke!

 

The Technical Data section of the Factory Service Manual here: http://foxed.ca/rx7manual/manuals/19...nical_Data.pdf states it sould be A.P.I Service GL-4 or GL-5 SAE 90 for both trans and rear end. I think 3 quarts sould be enough to do both. Make sure to get the limited slip additive for the rear end.

The drain for the trans is on the bottom of the flat section and the fill is forward and about 6 inches up the trans. Fill with a little hand pump until fluid starts coming out the fill hole. If you question it is full, pull the pump tube out and wait a couple of minutes for the fluid to settle. Then try filling again.

Same process for rear diff except put the limited slip fluid in first after draining the old stuff.

If the diff has a leak it could be the center section or axle seal.

 

Transmission fill bolt is 17mm IIRC. Strongly suggest you remove the fill bolt FIRST before drain plug, that way, if the fill bolt is seized you didn't just drop all your oil with no way to replace it. Also, you should put a few teaspoons of the same gear oil in from the shifter hole. It's not connected to the main Trans oil supply, but can use a little in the top to assist with smooth shift lever action.

Also, don't skimp on the GM LSD additive for the SE rear, as the additive is required for the friction plates to slip properly, and you'll destroy it without the right lube and GM stuff. One bottle is all you need, then 90wt gear oil until full.

 

I use Red Line 75W90 synth
(NOT the "NS" variety) or an equivalent which includes the friction
modifiers.
And the GM additive mentioned here by others.

Stu Aull
80GS
Alaska

 

Thanks guys! That's really helpful