2001 Pathfinder Manual Transmission/Differential Help Please

[little_tubby]

Hi folks, first post from a newbie and need some assistance - I will try to make this short & to the point:

- 2001 Nissan Pathfinder XE, 5spd. manual, LS Diff, 77k (Canadian)
- had the mechanic change out, transfer case, manual transmission, front and rear differential to Motul 75W-90 (little to no prior research)
- noticed a "chattering" or "buzzing" sound mid-vehicle almost immdiately when engine is cold and speed is over 40/kmh. the sound goes away once the engine gets to temperature.
- (did some research) changed the transfer case to Dexron III per Nicoclub and dealer advice (no resolve to the sound)
- changed the manual transmission to Redline MT-90 (no resolve to sound)
- still must change rear differential to Motul 75W-90 LS

Can one of you provide some perspective as to what is likely going on and the resolve to this issue? Thank you in advance.

[Towncivilian]

Welcome to NICO.

The fluid levels in the differentials, transfer case, and transmission are all correct?

75W-90, Dexron III, and Redline MT-90 are all proper fluids that should have adequate cold flow capabilities. I'm inclined to believe that the lack of LS additive in your rear differential may be causing your issue. Let us know if anything changes after the fluid change (or LS additive addition)!

[little_tubby]

Unfortunately, the differential fluid change did not result in a change in noise level when the vehicle is cold (32F or below). The noise sounds like it is right under me, and when i paly with the manual shifter, I can decrease the noise somewhat which indicates to me I may have a manual transmission issue since I changed out the fluid. Is it possible I could have damaged anything when I dropped the transmission fluid and replaced with the Motul gear oil? I may have put 20 miles on it, then changed it to Redline MT-90.

Thanks for any feedback.

[Towncivilian]

I can't imagine just 20 miles with the incorrect fluid would've resulted in damage. Have you verified the fluid level? The total fluid capacity is about 5.4 quarts for 4WD manual transmissions.

Have you greased the front driveshaft recently? I doubt it's related, but it's a good idea to do every oil change (or sooner if water entry is possible) anyway.

[donald]

my apologies if this thread has been resolved offline, but curious if there has been any activity or new findings?

I'm not experiencing any of the described issues (God forbid), I'm just being curious