Rear diff groan/moan after fluid change.

Hello!

I changed the 3 quart rear differential on my 2006 Prerunner 2WD double cab a few days ago and noticed today that on harder turns at low speeds in either direction, it sounds like a groaning sound is coming from the rear diff. Being this is the only thing I've done other than tighten the spare tire up a little firmer since never noticing this issue, I am assuming something is up with that. I drained the oil at roughly 127.5k miles and it was pretty dark/thick as well as some decent metal shavings on the drain plug magnet. I put 3 fresh quarts of Valvoline Flexfill SAE 75W-90 Full Synthetic Gear Oil till it dripped out the fill hole, new crush washers, torqued it to 36lbs fill/drain and off I went. Now I am noticing this noise and wondering what I should do. Should I use some sort of additive/thickener if the gears are worn from potentially this being the first gear oil change? Should I be using a thicker oil all together instead? Thanks!

Amazon link to gear oil used:

$61 Valvoline Flexfill SAE 75W-90 Full Synthetic Gear Oil 1 QT, Case of 4

https://www.amazon.com/dp/B08K9CGB6Y?ref=ppx_yo2ov_dt_b_product_details

 

2007 prerunner here. I had the same thing happen after I changed mine. After some reading I found some other folks suggested that the older limited slips still needed additive despite it already being in the gear oil. I added this and it was much better:

$10 Friction Modifier Positraction Additive for Limited Slip Differentials

https://www.amazon.com/Yukon-Gear-O...d=1660762832&sprefix=yukon+add,aps,159&sr=8-3
You may have to drain out a little bit and then add it.

 

@blue_runner thank you very much, I will go ahead and do that! I was also unsure if I needed to do this since the fluid claimed to have the additive, puts me at ease!

 

@blue_runner I should also ask how much of the bottle you added to the 3 qt rear diff? Thanks!

 

It's been a little bit since I did it, but I think I used around 2.5 quarts plus the additive.

 

awesome, thanks for the quick response and easing my headache!

 

@blue_runner update: I drained all the synthetic fluid, and added 1 whole bottle of the suggested Friction Modifier Positraction Additive for Limited Slip Differentials by Yukon. I also, after reading on many other threads/forums, found many people had issues with synthetic fluid in their Taco's rear LSD and opted to go with conventional 80W-90 just for a little added weight as well. The noise immediately went away after driving off from changing the fluid out. I will keep this thread informed if this issue doesn't come back so others know to either not use synthetic all together, or at least add an additional bottle of LSD friction modifier to it EVEN IF it has claims of containing the additive already.

Another note: I drove with the Valvoline synthetic for about 120 miles, there is still a weird "popping noise" occasionally on acceleration/braking and turns, hard to say as I only drove about 2 miles since the change to conventional oil and I hope it goes away. I am pretty sure it wasn't there before messing with the rear diff oil. There wasn't any concerning new metal shavings or anything after the change so I don't suspect any worrying damage was done. Will also update if that popping noise goes away now that it's swapped out.

 

I’m experiencing the same, just drained and refilled rear diff with Mobil 1 fully synthetic

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 with the lsd additive, and the lsd is groaning! Back to the auto store for more friction modifier additive!!

 

@milescf maybe even go as far as to use conventional instead of synthetic, I had 0 noise/issues after putting conventional + friction modifier, good luck!

 

Yeah, I’m standing in autozone now wondering if I just need to drain that 3 qts of synthetic on the ground and start over. Pissed! (Wouldn’t drain on ground, obviously)

 

@milescf I guess personally I'd buy 2 bottles of friction modifier, then the conventional, and try just adding the friction modifier and returning the other 2 if that works, or else having it all on hand just in case it doesn't fully resolve your issues!

 

I drained enough gear oil to add the modifier, and I the groaning and bitching immediately went away, so I’m running the full synthetic which already has the additive + 7 oz (one full tube) of the modifier. I guess if it grenades I’ve got the green light to order the harrop e-locker that’s been for sale in marketplace.

I’ll post again after road trip this weekend to let you know how it went.

 

Hey guys, big thanks for posting all this. Just did a diff change on my 08 and had similar experiences. Probably should've researched and scanned through before doing it. Anyway, had the nasty sound after using Valvoline syn, redid following above....now grinding and slipping!

 

After reading this article I’ve been using Dino oil in my diffs

https://eastcoastgearsupply.com/ft-2536-ecgs-gear-oil-recommendation.html

 

I always use the cheap gigantic 5 quart bottle available at auto parts stores and never had an issue. Didn't see much of a point in putting full synthetic in the rear diff tbh

 

Amsoil Severe Gear 75W90 in my Prerunners diff. No noises.