Mustang Gear Oil

[buck91]

So I'm probably going to do the gear oil in my Mustang at some point this winter. Its a basic Ford 8.8 with the trac-lok, although I did upgrade it to the carbon fiber clutch packs a number of years ago. Never had any issues with basic gear lube and the motorcraft additive. About two years ago I had a very good local shop throw some used 3.73 gears in it for me. They did a fine job but advised they were unable to eliminate whine being used gears and all. This is fine, its a weekend car with decent exhaust and a loud stereo and a little whine is fine. That said, what would be the best option for gear oil to reduce this noise? Thinking XXw-140 most likely, and I'll likely stick to dino/mineral oil since this is primarily a fair weather vehicle... Will it even matter much, or just stick with whatever 8xW-140 I can find locally? Sometimes this car does see late season use if road salt hasn't come out yet, whats the lowest temp such a heavy gear oil is good for?

 

[SwampSurvivor]

In my experience, it doesn't matter if its 75w90 or 85w140, it's going to whine if it's going to whine and it's going to be equally as noisey.

 

[Black_Thunder]

I used 75w140 in all my fords with the 8.8 because they were' spec'ed for it like my 95 t-bird and late 90's explorers, only time i used 80w90 is in my older f150's


either Valvoline, Mobil, or even Supertech 140's are fine. might wanna try some friction modifier in it regardless if its rated for l/s, It helps with foaming.

 

[Linctex]

The only way to reduce whine is to either machine the gear teeth to the correct profile... or possibly adjust the pinion depth (often, a little "deeper" does help). This can only be done by taking it all apart.

 

[Oildudeny]

Any brand 85w140 will do but definitely add the friction modifier

 

[zeng]

Yes, pick a mineral in 85W140.
If you may, do consider Lucas for its high KV40C of 390 - 400ish cSt.
Tightening pinion shaft locknut by 1/8 - 1/4 turn may help further with the whines .