Wedge TR 7 Differential Lube

[JamesK]

Going to change the differential in my 1980 TR 7 and wondering what you think of going to Mobile 1 synthetic gear lube? I have no leaks there now and hear rumors that if I change to a synthetic I might start having leaks?

 

[Darrell_Walker]

I put Castrol Synthetic in my TR8 (which may or may not be as "synthetic" as Mobile 1), and haven't had any leaks.

 

[TR3driver]

An anecdote, may or may not be relevant:

I had a bad experience with Mobil 1 synthetic motor oil in my Buick "hauler" station wagon. It had been fed a steady diet of Valvoline full synthetic, but I had been given the Mobil 1 and decided to try it. Oil consumption went up drastically, from something like a quart every 4000 miles to a quart every 1000 miles or less.

Fortunately it gradually dropped back down again as the Mobil 1 leaked out and got replaced with Valvoline.

I shan't be repeating the experiment with gear oil. Valvoline full synthetic seems to work very well for me in all my cars, I see no reason to take a chance on something else. For example, my previous TR3A differential was already well worn when it came to me (almost 1/4 turn backlash at the driveshaft). Some 200,000 hard miles later (including 1st in class at the VTR 2000 autocross), it was still working fine. Unfortunately I sold it after the wreck without ever inspecting inside; but I have not heard any complaints from the buyer so I assume it is still working today.

 

[tr8todd]

Any combo of synthetic 70/80/90 gear oil will work well. Don't forget you will need a new gasket. You have to remove the cover to drain it. Clean out inside well with some brake cleaner, blow it dry, install new gasket and fill it up till the fluid comes out the fill plug. If you want to make sure it doesn't leak, coat each side of the gasket with a little RTV and only snug the bolts. Go back a little later and then torque them down. While your in there have a good look at the wear pattern on the gears, and check for excessive backlash.