Do I need to match LSD additive?
- Thread starter jtmagde
- Start date
When does the chatter happen exactly?
I think most of the oils that say they have LS additive don't have nearly as much as adding your own, so you may still need to add some until it has the desired effect.
From what I've gathered, synthetic can do that even with the additive, and so it seems some are adding more. I just don't know how to find the right additive or if it matters. I'm asking Valvoline but their answer will likely be not very helpful. We'll see.
I also have a Tacoma with a mechanical LSD. I found long ago that the only way to permanently avoid chatter is to fill 3 qts of 80w-90 Valvoline and one tube of this LSD friction modifier:
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Also, I don't think these differentials work well with synthetic fluid. It has to be dino.
Correct. I haven't found a technical explanation for this, but conventional + additive seems to be the only combo that works well consistently on these trucks.
At normal temperatures (about 40-50 deg C), the 80W-90 has a much higher viscosity than the 75W-90 (synthetic ones).
It's not the appropriate substitution, especially the Valvoline FS one, 75W-110 is closer in viscosity specs.
See this table here: https://bobistheoilguy.com/forums/threads/gear-oil-80w-90-versus-75w-90.338642/page-2#post-5707082
It's not the appropriate substitution, especially the Valvoline FS one, 75W-110 is closer in viscosity specs.
See this table here: https://bobistheoilguy.com/forums/threads/gear-oil-80w-90-versus-75w-90.338642/page-2#post-5707082
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Manual says 80W-90 below 0 degrees fahrenheit. I live in the desert, so not sure if I should switch it for 80W-90 or if the 75W-90 is better for high temps and towing. I do a lot of towing.
Valvoline was surprisingly helpful. Answered the phone right away. Said it technically should be ok, and the Valvoline oil has 4oz additive per quart. That seems strange though, since that would mean I have 12 oz additive in there with 3 quarts. I asked again, and they again said it has 4oz per quart, but this seems odd to me. How much additive are people using with the 80W-90?
The 75W-110 is better for higher temps too.
Valvoline 75W-90 has the lowest viscosity at 40C from the pack of 75W-90 (look on the table) and if your diff was speced to 80W-90, IMO, it's bad to use that Valvoline, no matter what you add into it.
The only thing annoying about 75W110 is it's more or less a specialty grade only made by Amsoil, Ravenol, and Redline and it carries the price.
Before adding more FM. Try doing backwards, full lock steering, figure "8"s to work the fluid into the clutch packs. This has worked for me many times. Remember, if you put too much FM in the clutches might slip making the "posi" a "open".
I don't think that is correct. 4-5% treat rate is typical for differential fluids which would equate to about 1.6oz of additive per quart.
$20 a Qt. That's not the end of the world.
This is odd. It also points to a bigger problem. When again is it happening exactly?
My 2007 Tacoma would chatter on synthetic 75w90, no amount of additive would smooth it out. I went back to 80w90 and 4oz of additive and it was as smooth as ever. From then on it got 75w90 in the front diff and transfer case and 80w90 with 4oz of additive in the rear. I don’t own it anymore but I know the new owners and they haven’t had any trouble out of it. I traded it with 87k a little over 2 years ago. It has well over 100k miles now with a lot of heavy towing during its time with me. Synthetic isn’t needed in these rear diffs, they hold a lot of fluid for their size. After a couple changes to get the break-in wear flushed out, the fluid will stay nice and clean even after 30-40k miles.