Rear end vibration after rear diff oil change HELP

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I'm posting for my uncle who has an 06 Tacoma TRD Off road that he bought new. He's decided to keep the car even longer since it's been treating him well and asked me to change all the fluids. The car has 216k miles and has only had oil changed and the cabin filter after the fan failed. I believe spark plugs are original! since it's Denso on one side and NGK on the other. Engine Air filter was essentially clogged. Despite all of this, the car never misfired.

Anyways, after I changed the rear diff, the rear end has been vibrating bad, especially around 30-50mph. Here's what I did in order:

1)Valvoline 75w90 Synthetic
Vibration started, read about synthetic was a no no. He drove about 400 miles in that one week.

2)Valvoline 80w90 conventional
Vibration still there

3)CRC Limited Slip 7oz
No change

4) GM Limited Slip Oil 4oz
No Change

5) Coastal (Autozone House brand?) 85w140 conventional
Less vibration but still there

I did not see any LSD sticker on the rear diff nor the door jamb. There's a sticker for C9. It has an electronic diff lock.

Was I wrong to change the rear diff at 216k miles for the first time? It came out dark and thick with a goo on the magnetic drain plug.

What are the solutions to get rid of the vibrations?
 
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I don't see how changing gear oil could cause vibration. Something else changed/broke coincidentally when you did this. Wheel weight come off? Bad spark plug/wire? Tire break a belt?
 
I tried RP Max Gear one time and it gave me vibration and wheel hop. Drained and refilled with Amsoil AGL and have been happy ever since :^)
 
I should mention that it only vibrates when you accelerate. Once you let off the gas, it's smooth. Theres no noise.
 
The TRD Off-Road should have a manual electronic locking rear differential; there will be a button for it left of the steering column. The TRD Sport has a limited slip.

So, if it is the Off-Road, any 75w-90 should be fine; limited slip additives are not recommended. I had a 2008 with the same package and used Mobil 1 75w-90 without any issues.

You weren't wrong to change the fluid, although mine looked nasty at 72k miles. I tell most people to do it at 60k.

I can't account for the vibration, but check the fluid level; make sure it's right at the fill plug when the vehicle's level. There should be a bunch of grease fittings on the driveshaft too. Make sure you take care of those.

Grease fitting reference.
DIY transmission flush.

Good luck. I'm sorry I couldn't be of more help.
 
Yes, I removed fill plug then drain plug. Reinstalled drain plug and filled until it dripped out of the fill hole. I didn't raise the car, just left it leveled.
 
Coincidence. Gear oil might make a diff whine, moan, or chatter (if it's limited slip and you use non friction modified fluid). But it won't make it vibrate. I'd like at the driveshaft and u-joints
 
I don't know what it is that causes problems when changing diff oil for the first time after a lot of mileage but it must be common.
I took my Falcon to a mechanic yesterday to change my diff oil whilst he serviced my transmission (sealed unit) and he warned me against changing the 15 year old diff oil with 200k on it saying it might make it worse (he must have presumed I was changing it to try fix something but it's fine and I just wanted fresh oil!). I told him to do it anyway and he said it came out completely black but I have had no problems so far!
 
I suspect the oil cooked down to a pretty thick effective weight over the years.

Your trend shows the 140 wt make it a little more quiet.

Try adding some Lucas to thicken it up a little more. See if it trends quieter.
 
By now I hope you realized that the gear oil has nothing to do with your vibration. Check the u- joints. Don't bother greasing them (probably no fittings) they would be shot by this stage. Also a weight could have been knocked off the driveshaft.Don't bother with Lucas to thicken the oil.
 
Originally Posted By: Oil Changer
It always seems to be a coincidence when Valvoline is involved.


Nonsense. A company who has been producing oil since 1866 doesn't stay around by producing a bad product.
 
I'll tell you what is a coincidence....

Originally Posted By: Oil Changer
It always seems to be a coincidence when Valvoline is involved.
 
Originally Posted By: Lubener
By now I hope you realized that the gear oil has nothing to do with your vibration. Check the u- joints. Don't bother greasing them (probably no fittings) they would be shot by this stage. Also a weight could have been knocked off the driveshaft.Don't bother with Lucas to thicken the oil.


In addition to the above comment(s) you might grab the U-joint at the drive pinion and see if there is any play. It could be a worn drive pinion bearing.

Also, take the cover off the pumpkin and with the rear jacked up rotate the wheels and drive shaft, and see if there are any teeth missing or broken on the both the ring gear and drive pinion. The spider gear and its bearings should also be chccked.

I have also seen a badly worn axle bearing send vibrations down the axle shaft to the diffy and cause all kinds of havoc.

So, there are a lot of mechanical factors back there that could cause this.

I don't see how ANY lube could have caused this problem.
 
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