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2013 ATS 3.6L Luxury
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Discussion Starter #1
I originally did the diff fluid sometime after I got it used w/17k on it in 2014. Fluid didn't look too bad, but it had a disturbing amount of crud stuck to the magnetic tips on the fill & drain plugs, like a thick paste. Probably break in material worn off the gears. So decided to do it again now at 33k. This time fluid looked great, minimal crud on magnets. Some info for DIYers on the forum:

I wouldn't lift from the diff, it sits in bushings, might damage them, might not. Why risk it. I lift from the cross member directly behind the diff.
cross member S.jpg


I put the jack stands inside the brackets about a foot in front of the rear wheel deflectors.
Stand trimmed S.jpg



For fluid, I went with factory fill, listed as 88863089 for open diffs in this thread:


It's been superseded by 19352759. Yeah I could have bought a quart of something else with GL-5 synth spec for less, but with the rep the seals on our diffs have, I wanted GM specified fluid. 21 bucks shipped off Ebay. I used the Harbor Freight transfer pump:


I would prefer if hoses slipped over barbed tips that I could clamp for positive retention, but best I could do was just to jam them in there tight as possible and not apply too much pressure when pumping. I didn't want to have bottle tip over, so I made a holder for it from the Ebay box.
Box S.jpg


The plugs have rubber gaskets, make sure you don't lose them; clean, lube them with fresh fluid for reinstall. Aren't very tight, easy to loosen with a 3/8 ratchet. Unless you're poor Sergio526; plugs on his diff were probably over torqued with a stun gun by dealership techs after a repair. Make sure the fill plug comes off before you remove the drain plug! I guess you could try to fill thru the vent hole if for some reason fill plug doesn't come off.

Good pics of plugs and vent in this thread:


My vent has always been clean, never had to mess with it, cap nice and loose riding on the spring. But there has been some confusion as to size of wrench needed to remove vent, some saying it's a 16, others saying that didn't fit. I was curious so decided to check. 15mm goes on it, but it's too loose. 14mm just starts to go on, it but doesn't go all the way on. At least on mine, it's 9/16". I put an offset wrench on it and tried to loosen it. Tight, so I left it alone, didn't want Murphy putting in an appearance with me not having a replacement on hand if I broke cap off it.
Vent wrench S.jpg

It looked like a ratchet with a deep socket might also work with swing room available above diff, just need a socket with straight internal walls to clear cap.
Vent ratchet S.jpg


If you are going to pop off vent for cleaning or RnR, hit the shelf it sits on with a small paint brush so any crud on there doesn't fall in. The fluid change itself is pretty easy as long as you have equipment needed to do it, good way to save some $ and make sure it's done right.

Oh yeah, I set down a big piece of cardboard because no matter how careful I am, I always seem to get a drip or 2 outside the drain pan. If you do happen to get some on the concrete, grind cheap cat litter into it with your shoe, lifts it right out.
 

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2014 ATS 2.0T 6spd manual Performance RWD
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ADMIN CAN WE STICKY THIS?

Nice, thank you! How did you know how much fluid to put in the diff? I've heard you just fill it up to the top?

I have a 6spd manual RWD ATS w/LSD, would the fluid I use be different than what you listed above?
 

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Man I love these write-ups, even the little details like securing the bottle inside a cardboard box... I'll start doing this when filling 5qt oil containers with used oil to drop off at AutoZone (I usually spill every time). Great post!
 

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2013 Luxury ATS 2.0T Manual
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Nice, thank you! How did you know how much fluid to put in the diff? I've heard you just fill it up to the top?

I have a 6spd manual RWD ATS w/LSD, would the fluid I use be different than what you listed above?
1 liter will get it up to the fill plug (US spec says 1 quart, but if it's something you want to do somewhat regularly, get two quarts to start. Empty one into the diff and then pull from the other until it's "full" and then put that bottle aside for the next time to do the same thing). For us with the limited slip differential, it is a different fluid. Well, it's basically the same except it has a Limited Slip additive so that the clutches in the diff can grip. From the other thread:

Rear Axle (Non-Limited Slip Differential)
Gear DEXRON MTF 75W-90 (GM Part No. 88863089)

Rear Axle (Limited Slip Differential)
DEXRON LS Gear 75W-90 (GM Part No. 88862624, in Canada 88862625)

Although it looks like there might be some new part numbers based on above.
 

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2013 ATS 3.6L Luxury
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Discussion Starter #7
How did you know how much fluid to put in the diff? I've heard you just fill it up to the top?

I have a 6spd manual RWD ATS w/LSD, would the fluid I use be different than what you listed above?
The 1st link in my post lists capacity for diff with LSD at 1.0 L, but I could not find anything specifically for the open diff as used in my Lux. I thought I read somewhere that the LSD diff was larger?

So 1st time I did it, I removed the fill plug and stuck my finger in there to check level. It was just under fill hole. I then took an empty oil quart bottle, popped a small funnel on it, and opened up the drain. Unfortunately I missed some of the fluid, maybe a couple ounces, so didn't get an exact reading. Ended up with about 28 ounces in bottle.

When I filled, I stopped when fluid just started to drip out of fill hole. Had a little bit left in bottle. So filling to the drain hole is probably fine. That's how it was done on 10 and 12 bolt GM diffs.

LSD diffs require a fluid with friction modifier so you don't get diff clutch chatter around corners. PN as listed in Sergio's post still available at numerous places online, including Ebay for same 21 bucks shipped I paid.
 

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2016 ATS Sedan / 2.0T / RWD / 6-AT
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86 Posts
Just did it today. Interesting how much "stuff" the magnetic plugs have picked out of the oil ...

But i refilled without having the car jacked up. There wasn't that much space underneath the car but I wanted to have the car as even as possible to get the right oil level.
A car pit would have been worth a mint :D

579728

579729

579730

579731
 

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17' 6MT ATS Carbon Black, 09' Malibu, 08' Infinity G35x, 04' Ion Redline,
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FYI, When you guys do this you need to have the car level, not doing so will make fluid come out sooner when filling
Per the manual on page 383 Fill lvl is 1.1 qt, Which is what I put in, and about what came out.
I have a RWD LSD ATS and used Redline 75w90.
 
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