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.