[BDivine76]

Looking for a little help here. I'm about to change the rear diff fluid (found the part number in another thread already) and I want to make sure I know the drain and fill bolts. I've seen other 6th Gen posts on this, but so far I haven't seen photos for an SS 1LE, ZL1, or ZL1 1LE.

Just a little paranoid and looking for some confirmation. Thanks in advance for the help.

On another note - I did find a dealer in So Cal that has the new oil and sold me 12L...even at a discount! That said, be careful. My local Chevy dealer where I bought the car tried to sell me a standard 0W-40 and claimed it was the same thing.

[trz174]

Originally Posted by BDivine76

Looking for a little help here. I'm about to change the rear diff fluid (found the part number in another thread already) and I want to make sure I know the drain and fill bolts. I've seen other 6th Gen posts on this, but so far I haven't seen photos for an SS 1LE, ZL1, or ZL1 1LE.

Just a little paranoid and looking for some confirmation. Thanks in advance for the help.

On another note - I did find a dealer in So Cal that has the new oil and sold me 12L...even at a discount! That said, be careful. My local Chevy dealer where I bought the car tried to sell me a standard 0W-40 and claimed it was the same thing.

I just did it on my 18 ZL1. Maybe 30 mins once it’s setup to start work. I just took it off the lift so no photos.

The differntial drain plug is on the rear at the bottom and is removed with a 3/8” rachet (square hole). After it drains and you put the drain plug back in (snug, don’t squeek it), fill it with fluid. The fill hole is on the drivers side about half-way up the differential and you need to use a 5/16” or so hex wrench. It took about 1 2/3 bottles of GM differential fluid. I bought one of those fluid transfer hoses from Advance Auto. It screws on top of the bottle and has a 16” clear line. Hook the fill hose to the bottle and position the bottle near the driver side wheel and the clear hose goes almost straight into the fill plug. Squeeze the bottle, be patient and let air in the bottle until it’s empty. When the differential is full (second bottle), fluid will leak out of the fill hole into the drip pan or on to the floor if you forgot that part. Let it run out of the fill hole until it stops, clean everything up with brake cleaner and put the fill plug back on and snug it up.

NOTE: There is a small fill hole on the passenger side of the differential near the top that IS NOT (REPEAT NOT) the differential fill. This plug is for the differential cooler and uses transmission fluid.

Hope this answers your question. Good luck!

[BDivine76]

Originally Posted by trz174

I just did it on my 18 ZL1. Maybe 30 mins once it’s setup to start work. I just took it off the lift so no photos.

The differntial drain plug is on the rear at the bottom and is removed with a 3/8” rachet (square hole). After it drains and you put the drain plug back in (snug, don’t squeek it), fill it with fluid. The fill hole is on the drivers side about half-way up the differential and you need to use a 5/16” or so hex wrench. It took about 1 2/3 bottles of GM differential fluid. I bought one of those fluid transfer hoses from Advance Auto. It screws on top of the bottle and has a 16” clear line. Hook the fill hose to the bottle and position the bottle near the driver side wheel and the clear hose goes almost straight into the fill plug. Squeeze the bottle, be patient and let air in the bottle until it’s empty. When the differential is full (second bottle), fluid will leak out of the fill hole into the drip pan or on to the floor if you forgot that part. Let it run out of the fill hole until it stops, clean everything up with brake cleaner and put the fill plug back on and snug it up.

NOTE: There is a small fill hole on the passenger side of the differential near the top that IS NOT (REPEAT NOT) the differential fill. This plug is for the differential cooler and uses transmission fluid.

Hope this answers your question. Good luck!

It does! Thanks for the help. This is what I thought, but I haven't done this yet and wanted to be sure.

[1967RS327]

When I changed mine I flushed the 4+ quarts of oil out of the cooling system loop. Draining and refilling 1.5 quarts in a nearly 6 quart total capacity system doesn’t seem like it would do much..

[Whitespeed]

Originally Posted by 1967RS327

When I changed mine I flushed the 4+ quarts of oil out of the cooling system loop. Draining and refilling 1.5 quarts in a nearly 6 quart total capacity system doesn’t seem like it would do much..

That's not diff oil. That's transmission oil. There's a heat exchanger in the diff that cools the diff with the transmission oil.

From Car and Driver:

Tech Highlight: Cooling That Goes to 11

That the ZL1 packages 11 heat exchangers into its powertrain shouldn’t surprise you. Six hundred and fifty, after all, are a lot of ponies to chill. Of the 11, seven are air-to-liquid coolers and four are liquid-to-liquid. There’s an air-conditioning condenser packed in there as well because drivers need cooling, too. Chevy engineers came up with a novel solution for keeping the ZL1’s active differential from cooking its lube. Cooled transmission oil is routed to a heat exchanger inside the differential housing where it extracts heat from the differential oil. An auxiliary transmission cooler is packaged horizontally and sits under a wind-*tunnel-designed cover that protects it from road debris and increases flow through its core. Cool.

https://www.caranddriver.com/reviews...st-ride-review

[devnull]

Here is the writeup you are looking for --> https://www.camaro6.com/forums/showt...highlight=diff

It's for the SS 1LE, but the E-Diff and procedures are the same here.

You will use a little less than 2qts, and no flushing is needed.

Pop the fill plug first (it is above the drain plug), then the drain plug. Let it drain until it stops, then clean those dirty plugs (they are magnetic as you will see below, they pick up a lot of metal). Here is a pic of the drain plug hole while draining and a pic of the nasty metal filled fluid you will find (don't freak, that's normal and only has 1,500 miles on it).

Put the drain plug back in, put the pump in bottle one, and start pumping! Keep going until the second bottle is almost out (it will start to seep out of the fill plug).

Hope that helps a little...

[1967RS327]

Originally Posted by Whitespeed

That's not diff oil. That's transmission oil. There's a heat exchanger in the diff that cools the diff with the transmission oil.

From Car and Driver:

Tech Highlight: Cooling That Goes to 11

That the ZL1 packages 11 heat exchangers into its powertrain shouldn’t surprise you. Six hundred and fifty, after all, are a lot of ponies to chill. Of the 11, seven are air-to-liquid coolers and four are liquid-to-liquid. There’s an air-conditioning condenser packed in there as well because drivers need cooling, too. Chevy engineers came up with a novel solution for keeping the ZL1’s active differential from cooking its lube. Cooled transmission oil is routed to a heat exchanger inside the differential housing where it extracts heat from the differential oil. An auxiliary transmission cooler is packaged horizontally and sits under a wind-*tunnel-designed cover that protects it from road debris and increases flow through its core. Cool.

https://www.caranddriver.com/reviews...st-ride-review

Thanks for posting this! I’m really glad I haven’t primed the cooling loop yet, I just drained it a couple days ago and it’s still sitting in my garage. I really should have done more research before I dove into this lol. Any idea what type of trans fluid goes in the cooling loop? I have to say though it was dirty fluid that came out. Not like what came out of the diff but still pretty dirty.

[Whitespeed]

Originally Posted by 1967RS327

Thanks for posting this! I’m really glad I haven’t primed the cooling loop yet, I just drained it a couple days ago and it’s still sitting in my garage. I really should have done more research before I dove into this lol. Any idea what type of trans fluid goes in the cooling loop? I have to say though it was dirty fluid that came out. Not like what came out of the diff but still pretty dirty.

From that C&D article, it sounds like whatever bathes the transmission gears also circulates through the cooling lines, including the liquid to liquid heat exchanger in the diff. Not sure how to confirm that though.

Nigel

[dansap]

So I looked under my 2018 convertible zl1 today to change out the differential fluid and seen that it looks like both the drain and fill plug are on the drivers side. Being the first time I ever did it I was just making sure that I’m correct. If anyone could tell me positively correct I would greatly appreciate it.

[atx_traveler]

the vert doesn't have the e-diff, so it's like the one in the SS. both fill and drain are on the drivers side.

[dansap]

Originally Posted by atx_traveler

the vert doesn't have the e-diff, so it's like the one in the SS. both fill and drain are on the drivers side.

Thanks for the clarification. So I still use the same oil

[Bangkok_ZL1]

I got to get this done. Unfortunately, nobody has this diff fluid here. I messed up when I ordered from Jannetty Racing. I should have asked them to toss in a couple bottles. Next package that comes here needs to have them in there

[Biscuit.fr]

What is the difference between the initial one I have
And this new one GL-5 I didn’t know until this picture?
Tx for the answer

Same ref,
Same numbers
Except GL-5 (???)

[Biscuit.fr]

Has anybody tried the Motul 300 LS 75W90 instead?
(Contains also limited slip)
Should be good to go