65mechanic

Sup guys, I've had a whine coming from the rear end for a while now. I had to change out an axle shaft oil seal and when I re-added the gear oil I used Castrol Syntec 75w90 (Full Synthetic). Just wondering if I need to add some friction modifier or not/ Or if I'm damaging any rear end parts. Or if its just normal wear. Thanks. By the way, I bought the car with 3.73s and I've driven the car 30,000 miles since I purchased it.

cliffyk

Most synthetic gear oils do not need additional FM as they are already sufficiently "slippery". Does the rear-end whine only when turning or when traveling in a straight line?

I ask because when driving in a straight line the LSD clutches are inactive and FM or not would not matter. This leaves how long did you drive it with the leaking axle seal? The rear-end could have been damaged from running with low or no oil--what did they look like when you opened the pumpkin?

65mechanic

It was lower than I liked when I opened it up. I actually opened it up in my personal garage, and couldn't figure out. So I took it to my mechanic and he did the switch out. Yes, I did re-fill it when I took the cover off, but when I did the gears looked fine and there wasn't any metal shavings or anything like that inside the housing. I guess my question now would be "would it hurt to add the friction modifier with the synthetic gear oil?" But yeah, it was low, I'm not going to lie.

uberstang1

Sounds like bearing wine to me which could of been done from the low to no fluid.

65mechanic

Yeah, sorry. I didn't answer your question before. It really only whines when I'm in 4th or 5th gear letting off the gas. But, I do agree that the low fluid had something to do with it.