Gear whine after diff fluid change

Changed diff and transfer case with mobil 1 75w90. Old oil was dark but minimal sludge. May have slightly over or under filled due to my driveway but it's probably filled more than before. Now all I can hear constantly is whining gear noises but I'm not sure if it wasn't always there and I'm hyper conscious. Do older trucks just have whinier gears? Would new fluid make this louder instead of more quiet?

 

Check your manual for the appropriate transfer case fluid. I don't recall what the 2nd gen said, but the 3rd gen is a GL-4 75W fluid. Not the same as the GL-5 used in the diffs. However, I doubt this would cause noise. Ravenol makes a reasonably priced 75W GL-4.

I would double-check the fluid levels. If it was cold, it may take a bit for the fluid to seep into the axles. I haven't had a gear oil change cause any new noises. Many people use synthetics, but it seems most gear gurus tend to recommend just the plain dino oils for diffs. I doubt that would cause new noises, though.

 

Pretty sure I'm just noticing it more now. Also need to do the transmission so maybe it's showing it's age. Can you hear some gear whine just driving around town?

 

Well, I have a 3rd gen, and the diff whine is a well-known issue. Some people have it, some don't. My truck didn't have it, at least not that I noticed. Then I did a swap through ECGS to 5.29 gears, and now I have a whine. It's just a characteristic of the diff. I only notice it on the highway, though, not in town. Hopefully you are just now noticing it, but I'd still validate fluid levels to rule that out.

 

Some have said that all of them whine a little bit. I couldn't say from personal experience, my radio/tires/rear seat delete all provide enough noise that it hides that sound on mine.

Manual trans or auto? If manual, did you change that fluid at the same time as diff & t-case, and using same type of fluid? If auto this won't apply.

I don't see specs on your truck in the info block. What year? Lifted and how high? Locking rear diff, mechanical LSD, or just regular open diff? Has it been re-geared? Did you put any additives in?

 

Make sure you use a LS gear oil even with out an LS. My buddy had a Dealer use the wrong oil and they had re replace his F/R Diff. They went bad in a very short time. You didn't state year, early Gen 2's were non slip by at least 2010 they needed the LS oil. Non-LS can use LS without issue.

 

It could yes. On my 2010, I got more chatter accelerating out of corners with 75W90 in the rear diff. The chatter went away with 75W140.

If you have a 2005-2008 TRD Sport, be sure to add a tube of LSD additive to the rear diff.

 

I don't have the LSD and have never heard of adding LSD additive to a non LSD diff. 75w90 is recommended on here all the time for all of the diffs and transfer case and I'm not having any loud noises, just sounds a bit whinier than I recall.

I have the auto transmission but haven't gotten around to doing a drain and flush on it. It's on the horizon, I just don't have a flat place to do it.

Mine is mostly stock 2007 DC OR. I have 5100 at .75 in the front and 265/75/R15 tires.

 

Yeah, you don't need the additive unless you have a mechanical LSD. I just used the Super Tech dino 80W-90 in my stock diff, switched to Super Tech 85W-140 with the 5.29 gears. ECGS recommends Lucas dino, but said Super Tech dino was just fine. I've always avoided synthetics for gear oil, which matches ECGS recommendations.

 

My comment was it is ok, to use an LS in a non LS diff. Of course it is not necessary.

 

Your comment was pretty clear. Make sure you use a LS gear oil even with out an LS

 

I thought the same, but I think what he meant was to use an oil that is compatible/recommended/suitable for a LSD or posi-traction diff. These days it would seem hard to find a GL-5 gear oil that is NOT compatible, they pretty much all say that on the bottle. It's been like that since at least 2006 when I had my last mechanical LSD, which also required the additive (just because the oil says it is recommended/suitable for LS doesn't mean it already has the friction modifier).

I suspect his buddy's issue at the dealer was that either the tech used motor oil in the diffs, or it was a mechanical LSD and they did not add the friction modifier.

 

Replaced mine with Valvoline

$29 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 synthetic from the squeeze bottles. Chattering and whining ensued. Went back to standard Valvoline 75W-90 and used the friction modifier like I have been since the truck was new. Problem solved.

 

I believe the Mobile 1 Diff lube for our Rears has LS additives already in the oil, with that said Mobile 1 did change their formulation a few years ago, including diff oil, I recently went to AMS oil and higher number( 80w-90) .
My last Rear diff oil change the Mobile 1 was like water coming out. Mobile 1 has always been a bit noisier than other oils I have used.
I cant tell you its quieter as I have solid motor/trans and carrier mounts plus long travel suspension. But I can tell you is that after a long romp in the desert, a rest period and touching the rear housing netted way cooler temps.
https://www.amsoil.com/p/amsoil-severe-gear-80w-90-100-synthetic-gear-lube-agl/

 

A 2007 TRD OR would have a mechanical LSD. 2009 is when they introduced A-TRAC and went to electronic.

So you would need LSD additive/friction modifier.

But the presence of friction modifier should not make it noisier when driving down a straight road. You would notice chattering on turns when each axle is turning at different rates.

Mobil1 75w90 includes LSD additive in it.

So you should be fine.

 

I *think* there used to be 2 versions of the Off Road -- the 2WD had the mechanical LSD, but 4WD had the locker. It wouldn't be both. OP didn't say whether 2WD or 4WD, just that he didn't have the LSD. They used to put stickers on them, but after this many years that sticker may be gone.

 

The 8.0 tacoma, 2gen, diff with an E-locker IS a LSD diff.

 

You're saying Toyota sold a TRD Off Road that came with 2WD?

 

You are saying it has mechanical clutches that require the friction modifier? And locks as well? I did not know that.

They did with the 1st gens, at least in some markets. Not sure about the 2nd gen. I owned a 2006 Tundra that was a TRD Off Road, and it was 2WD with a mechanical LSD.

 

It’s not a mechanical LSD. Only the TRD sport 2005-2008 has mechanical.