4BW Rear Differential Fluid

[Raskolnikov]

For anyone who has changed the diff fluid in their 4bw: a little research has suggested that I should use

75w-85 SAF-EH Modified Low Viscosity Rear Axle Lubricant - 1 qt - GM (19418501)​

Can you please confirm that this is the correct fluid? GM wants $75.00 per quart!!! Is this made from unicorn tears?

 

[mfcentex]

I used ACDELCO 10-4131 from Rock Auto about 2 months ago.

 

[Sergio]

I got 2 qts from the Chev dealer. Asked for a discount and I think it was $46 a qt.

 

[leres]

I used ACDELCO 10-4131 from Rock Auto about 2 months ago.

For whatever reason, rockauto doesn't know the 19418501 part number but 10-4131 is currently $42.79 + tax + ~$10 shipping. $46 from the dealer sounds like a reasonable price to me.

 

[SladeX]

I followed tapout tuning's recommendation of running amsoil 75w90 in mine after the initial break in period. It's what I ran in my camaro 2ss 1le elsd and my corvette c7 z06 lsd. I'll be swapping out the transmission fluid in a few weeks as well once I'm satisfied it's broken in as well.

 

[mfcentex]

I followed tapout tuning's recommendation of running amsoil 75w90 in mine after the initial break in period. It's what I ran in my camaro 2ss 1le elsd and my corvette c7 z06 lsd. I'll be swapping out the transmission fluid in a few weeks as well once I'm satisfied it's broken in as well.

I did the differential at 2000 miles. Is the transmission needed just past break in? My last car I was swapping the transmission fluid every 20-30k.

 

[SladeX]

I usually do both my differential and transmission after initial breakin 2k miles as the parts should be mated well at this point. I find the fluid to be pretty full of metal shavings after breakin and don't want that crap recirculated for long.

 

[dwduck]

Does this fluid already contain the additive for the LSD or do you still need to add that in?

For anyone who has changed the diff fluid in their 4bw: a little research has suggested that I should use

75w-85 SAF-EH Modified Low Viscosity Rear Axle Lubricant - 1 qt - GM (19418501)​

Can you please confirm that this is the correct fluid? GM wants $75.00 per quart!!! Is this made from unicorn tears?

 

[SladeX]

The GM fluid should not require the modifier. I find the GM fluid much too expensive for what is essentially differential fluid with some modifier added. I use Amsoil in my cars, much more affordable and does not require friction modifier. I've tracked a C7 Z06 with Amsoil differential fluid and it holds up just fine for the eLSD both track and street use.

 

[jbawden]

I almost got suck into a veiled 'best oil' thread...carry on.

 

[dwduck]

The GM fluid should not require the modifier. I find the GM fluid much too expensive for what is essentially differential fluid with some modifier added. I use Amsoil in my cars, much more affordable and does not require friction modifier. I've tracked a C7 Z06 with Amsoil differential fluid and it holds up just fine for the eLSD both track and street use.

That's what I figured. I was wondering why they charge so much for it also.. do you mind linking the AMS oil product you use? Also are you sure it won't affect anything with the powertrain warranty?

 

[SladeX]

That's what I figured. I was wondering why they charge so much for it also.. do you mind linking the AMS oil product you use? Also are you sure it won't affect anything with the powertrain warranty?

https://www.amsoil.com/p/amsoil-severe-gear-75w-85-100-synthetic-gear-lube-svl/?code=SVLPK-EA&gad_source=1&gad_campaignid=20737228780&gclid=CjwKCAiA_dDIBhB6EiwAvzc1cD09hicmUT81nw5giLcVKomE3Qvmk30vgLO4dbVDG7HCoFl1Gh_CvRoCXUwQAvD_BwE&siteSwitch=true

It won't void any warranty. 4 vettes and 3 camaros and a 4bw across 30 years. Lots of drag racing and track time. Only times I've busted stuff was when I started building for power outside of warranty.