Mister Quickie

I got a letter from the shop stating I'm due, based on mileage, for a rear differential fluid change.
I looked on the 'net for a procedure on this and it's the same thing as what I did when I changed the transmission fluid.
Is it the same thing?

odonnell

Yes. It is a transaxle

azbanks

Typically transmission fluid is for an automatic transmissions and gear oil is used for our transaxles.

Jfrahm

It's hard to change the rear differential oil in a 944 without changing the transmission oil (real hard). It's also hard to want to, as there is no combustion back there the oil lasts a long, long time. I think the spec is to change at 60K but you could consult your manual and as always adjust to account for track usage, boat towing, etc.

If you have an LSD your transaxle oil choice needs to account for this.
-Joel.

Scott at Team Harco

Always use the heavy duty stuff if you tow a boat with your 944/951.

V2Rocket

if its over 30 ft, use heavy duty moly with a grease gun

SloMo228

If you're having the shop do it, make sure they use a GL-4 gear oil. Most modern cars use GL-5 oil and that's what's commonly available, but that type of oil supposedly attacks the brass synchros in older transmissions not designed for it.

odonnell

A lot of modern GL-5s don't have that problem, just use google to find out whether your choice in oil is safe for yellow metals.

Jfrahm

Don't be ridiculous, you'd never get a 30-footer up a slimy boat ramp with 951 gearing. You'd need at least a 928 with the 4-speed automatic.

Scott at Team Harco

Either that or a 914. They've got the weight right where you want it. Just below the waterline...

BoulderGeek

If you just got a 140K mile 944, would you swap out the gear oil in the transaxle, just to be proacive?

mrgreenjeans

Yes, Absolutely.

Do you have any record as to when it was done, or if it ever was ?

As to the transaxle lube, I have found Swepco 201 the one product that seems to deliver. It will transform your shifting into slicing warm butter with a hot knife. Your synchros will love the stuff......

If you have an LSD transaxle, as noted by 220 on your build code tag, the Swepco has what is required to extend the life of the clutches in there. No need to add a friction modifier.

Expensive , but oh so worth it. For track and / or everyday highway use.

NoRush993/951

I used Royal Purple gear oil which is safe for yellow metals and available at the local parts store.

BoulderGeek

I have records on the car, but haven't gone through them all, yet.

I will look for transmission service. The prior owners tracked the car lightly at PCA events, and paid good attention to the belt/WP services and suspension, so I hope they would have done it at some point.

The car definitely appreciates rev matching rather than having the synchro take up the downshifts.

GTgears

Because it is a transaxle you absolutely want a gl5 oil in there, not gl4. Swepco 201 is an excellent choice. Carquip on Arapahoe sells it and can do the device if you don't want to do it yourself.