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Not to beat this to death...but the "rear axle" is a commonly used term for the rear "differential", they are the same. The confusion is the term "eLSD" which, when discussing fluid, really is referring to the pump and clutches of the differential, which are what controls the locking degree of the differential. The exact words in the GM Service Manual are "eLSD clutch system lubricant"...the ATF fluid.
Last week I changed the oil in my Z51 M7 and after seeing this thread decided to replace the diff and trans fluids too. The diff fluid was nasty! The trans fluid didn't look that bad. I used Redline D4 ATF in the trans and OEM fluid in the diff. When I test drove it I was amazed how much smoother the transmission shifted. It feels so much better than before, although I didn't think it was bad before. I have the MGW shifter (shifts like a jeweled rifle bolt lol) and you can really feel the detail. The diff was 1/4 quart low from the factory. My Z51 is 3 years old and approaching 15k. Thanks Kracka for your original post!
As a side note, I purchased a 1 gallon pump-up type weed sprayer at Walmart for $4.98 and configured it to pump the fluids. It worked like a champ and not one drop was spilled.
The OP sure made it simple to go tackle this job. Some minor observations:
I'm not really sure that you have to have a flex-head ratchet. It was okay, but I think it would have been okay with a regular ratchet too. (The Harbor Freight ratchet that the OP linked to is a good-quality tool and I enjoyed using it.) I did need a 3" extension in addition to the ratchet. Maybe a 1.5" extension would have been handy too, but wasn't necessary.
I have a 2016 Stingray (non-Z51) with the M7 trans and I did not have any cooling lines in the way, nor were there any associated cooling fins. There was no plastic air deflector either.
Whoever suggested using aluminum foil to guide the outflow of the M7 trans fluid - thank you. It was well worth taking a moment to do that. I'll apply that technique to any vehicle I have that wants to make a mess when fluids get drained.
Please note that the fluid for the M7 drains in a gurgling fashion unless the fill plug is removed. When it's gurgling, it splashes some fluid around. So remove the fill plug first as the OP suggested. I was glad I was wearing eye protection when the gurgling/splashing happened. Once the fill plug came out, I took the goggles off.
I used only the official GM stuff linked above because the car is still under warranty.
Regarding the Plews pump suggested by the OP: I bought a couple of them. They worked well, sort of. The very worst part of the job and the longest part as well was using those pumps to pump the fluids. The Plews pump moves fluid 4cc's at a time. Considering that not every stroke is a perfect 4cc stroke, the reality of using this pump is that it takes 240-250 strokes per quart to get the stuff from the bottle to the trans or rear axle. In other words something like 1600-1800 strokes to get the job done. It was quite unpleasant.
Somebody suggested using an air compressor and a piece of tubing where you drill a snug-fitting hole in the cap and put the tubing in the hole, then put a small hole in the bottle and carefully use your air compressor's blower nozzle on the small hole to push the fluid out of the bottle. I wish I had taken this wise person's advice. If you're going to do this job, do yourself a favor and use the compressor technique. Also, don't use quarts if you can help it. It will be much more pleasant if you don't have to change bottles while pumping. Somebody else above suggested some kind of Walmart sprayer. That sounds good too. Just save yourself the endless pumping with the Plews.
FWIW, my car has almost 22,000 miles on it. There was no sludge or other residue in the M7 and the fluid was in pretty good condition. Yes, the new stuff seemed nicer going in. It is possible that the M7 shifts a little smoother with the new fluid. But it might be the same as "freshly-washed car syndrome" where the recent work changes your feeling about how the car drives. The rear axle fluid was a little bit dirty and there was a small amount of stuff on the magnets of both the fill and drain plugs.
I'm glad I did the job, but it seems entirely plausible that the factory interval is just fine. If you're not already obsessive about changing lubricants ahead of schedule, don't let this thread deter you from keepig on the official schedule. (I drive my car fairly hard but since it's a base Stingray it doesn't get tracked, thus track maintenance intervals don't apply.)
They are 2 completely different differentials, not 2 components within the same diff.
The standard diff is on the base Stingrays; the eLSD on the Z51 and up.
Keep in mind the eLSD (electronic limited slip differential) has 2 components, the ring/pinion gears which use gear oil and the electronic limited slip clutches which use fluid similar to ATF.
So yes, you're correct in that base Stingrays and the Z51/GS/Z06 are different differentials. However the eLSD units do have 2 components within, that take two very different fluids. Being an old-school gear head from the posi-trac days, I can see how the new technology could cause confusion.
I made the mistake in terminology that nearly lead to a much bigger and more costly mistake. I'll air my mistake for the benefit of others in hopes that you will not make the mistake that I almost made...
I wanted to drain the fluid from my rear axle (because if there were any metal pieces in there I would rather replace the fluid much sooner than later). The mistake started with a terminology mistake. The terminology mistake was that I was referring to the differential housing (the thing just in front of the mufflers) as the "differential". So when I emailed my service manager that I had drained the "differential" and then asked him what fluid to put back into the "differential" he simply replied back to use ACDelco 10-9394 Dexron VI Automatic Transmission Fluid [88865601].
Now that the fluid was drained I was prepping to put the fluid back into the "differential" and noticed that the fluid that I was about to put in was red, when the fluid that I removed was straw colored. This prompted a second email to my service manager, basically asking, "Are you sure?" This is when, we both began to realize that I was using the wrong terminology, which then resulted in misinformation and almost caused an expensive mistake.
With correct terminology, I now know that I drained the Rear Axle NOT the differential or the eLSD. With that correction, I now know that the straw colored fluid I drained was gear oil, and subsequently now know that the fluid that I need to put back into the rear axle is ACDelco 10-4034 Dexron LS 75W-90 Gear Oil [88862624].
After talking with my service manager today, I learned that changing the fluid in the eLSD is probably a dealer only job, not something that most of us could do. Changing the fluid in the rear axle, on the other hand, is relatively easy to do and certainly something that even those of us that are not very mechanically inclined can do.
I hope this helps clear things up for anyone that may be confused about what is the "differential" and what is the "rear axle".
I think you are still confused. We talking about changing the differential fluid.
The OP sure made it simple to go tackle this job. Some minor observations:
I'm not really sure that you have to have a flex-head ratchet. It was okay, but I think it would have been okay with a regular ratchet too. (The Harbor Freight ratchet that the OP linked to is a good-quality tool and I enjoyed using it.) I did need a 3" extension in addition to the ratchet. Maybe a 1.5" extension would have been handy too, but wasn't necessary.
I have a 2016 Stingray (non-Z51) with the M7 trans and I did not have any cooling lines in the way, nor were there any associated cooling fins. There was no plastic air deflector either.
Whoever suggested using aluminum foil to guide the outflow of the M7 trans fluid - thank you. It was well worth taking a moment to do that. I'll apply that technique to any vehicle I have that wants to make a mess when fluids get drained.
I bought one of these many years ago, if you like the aluminum foil you’ll like this even more.
Somebody suggested using an air compressor and a piece of tubing where you drill a snug-fitting hole in the cap and put the tubing in the hole, then put a small hole in the bottle and carefully use your air compressor's blower nozzle on the small hole to push the fluid out of the bottle. I wish I had taken this wise person's advice. If you're going to do this job, do yourself a favor and use the compressor technique. Also, don't use quarts if you can help it. It will be much more pleasant if you don't have to change bottles while pumping. Somebody else above suggested some kind of Walmart sprayer. That sounds good too. Just save yourself the endless pumping with the Plews.
Yep, I bought one of the plastic bottle pumps and it broke before I even got the tube full of liquid, so I had to improvise... Two holes in the bottle cap and a controlled air pressure on top of the liquid will push the fluid into the differential or transmission easily..
You are right that I first just poked a small hole in the bottle for the air tube, but then I realized if I put both tubes in the cap, I could just move the cap to another bottle and not have to mess with making another hole.
Another advantage of using the air is that if there are any leaks around the tubes, it only leaks air and not fluid like the plunger pumps.
Yep, I bought one of the plastic bottle pumps and it broke before I even got the tube full of liquid, so I had to improvise... Two holes in the bottle cap and a controlled air pressure on top of the liquid will push the fluid into the differential or transmission easily..
You are right that I first just poked a small hole in the bottle for the air tube, but then I realized if I put both tubes in the cap, I could just move the cap to another bottle and not have to mess with making another hole.
Another advantage of using the air is that if there are any leaks around the tubes, it only leaks air and not fluid like the plunger pumps.
Thats thinkin with your dipstick right there.. love it.
I changed my diff fluid when I did my 500 mile oil change and would recommend all do it.
Hypoid gear sets create quite a bit of metal flake as they break-in and it's good to get it out. Amazon had the GM diff oil quite a bit cheaper than the dealer-
It was about half a quart low when I drained it and it took 3 ounces less than 3 quarts to fill it.
This is my diff drain plug magnet and oil and my engine oil filter at 500 miles.
2019 Z51 A8 mag ride
Last edited by Makitso; 06-03-2018 at 03:28 AM.
Reason: model info
I changed my diff fluid when I did my 500 mile oil change and would recommend all do it.
Hypoid gear sets create quite a bit of metal flake as they break-in and it's good to get it out. Amazon had the GM diff oil quite a bit cheaper than the dealer- https://www.amazon.com/ACDelco-10-40...ar+Oil+-+32+oz
It was about half a quart low when I drained it and it took 3 ounces less than 3 quarts to fill it.
This is my diff drain plug magnet and oil and my engine oil filter at 500 miles.
2019 Z51 A8 mag ride
I agree with you man even more so if a person is going to keep his car for more then very a few years only.
Thats thinkin with your dipstick right there.. love it.
I used to do it that way but keep in mind that those OEM fluid bottles are not very strong. They will inflate as you put air in the bottle and you can fatigue the bottle until it ruptures. Don't ask me how I know.
I bought two of the cheap pumps that fit on a quart bottle last time I did my gearbox and went thru both of them, even while trying to baby them. I got this different pump this time, I'm going to use it for the outdrive on my boat I'm doing this week. I'll report back if it works better (or worse).
Please note that the fluid for the M7 drains in a gurgling fashion unless the fill plug is removed. When it's gurgling, it splashes some fluid around. So remove the fill plug first as the OP suggested.
I was always taught to remove the fill plug FIRST because if it is seized on (for any reason) then you can't FILL after you drain. At that point you would be royally screwed as the car would be un-driveable and require a flat bed tow away.
I found a Pennzoil one at O'Reilly that actually seems halfway decent so far.
Kracka - howdy neighbor, looks like I live about 45 min northwest of you!
I am getting my new 2019 Grand Sport in mid-October, planning to change the M7 and Diff fluids at about 1500 miles. If I use Mobil 1 75w-90 synthetic gear oil in the diff, do you know if I need to add additional friction modifiers, and if so how much extra to add?
Kracka - howdy neighbor, looks like I live about 45 min northwest of you!
I am getting my new 2019 Grand Sport in mid-October, planning to change the M7 and Diff fluids at about 1500 miles. If I use Mobil 1 75w-90 synthetic gear oil in the diff, do you know if I need to add additional friction modifiers, and if so how much extra to add?
Very cool! Maybe I'll see you out cruising around sometime. I often head north just to find some fun roads to burn up fuel on the weekends.
Unfortunately i do not know the answer to your question regarding the Mobil 1 gear oil, which is part of the reason I stuck with OEM back there. Ideally, I would like to do Mobil 1 next time around so this question definitely warrants some research. Hopefully someone else will chime in, and please report back with your experience.
Very cool! Maybe I'll see you out cruising around sometime. I often head north just to find some fun roads to burn up fuel on the weekends.
Unfortunately i do not know the answer to your question regarding the Mobil 1 gear oil, which is part of the reason I stuck with OEM back there. Ideally, I would like to do Mobil 1 next time around so this question definitely warrants some research. Hopefully someone else will chime in, and please report back with your experience.
Found the following from someone's question to Petro-Canada on BobIsTheOilGuy Forum: "Thank you for submitting your question to the Petro-Canada Lubricants website. Dexron LS Gear Oil 75W-90 is a synthetic extreme pressure automotive axle lubricant with limited slip top treat package. It is formulated for GM Axle Service Fill applications." Petro-Canada makes GM88862624 and it is a synthetic, so that makes me feel a bit better about using the AC/Delco branded gear oil, even though I would rather use Mobil 1.
04-20-2018, 12:18 PM
