Maxie2U

Twice? How often do you change your transmission fluid? GM recommends at 100,000 miles.

Kracka

First time @ 22k miles, second time at 37k miles. Long extended drain intervals are great for getting a car just out of warranty, but I'd rather keep it tip-top during my entire ownership so it continues to shift perfectly at a fairly minimal increase in ownership cost.

Phudu2004

Thanks for the guidance. I actually went ahead and bought the Redline ATF and the AcDelco like the OP used.

USCG

2016 Stingray (Base) A8 built Aug'15: Currently 13k miles and changed out the Diff Fluid with Dexron. I used a Harbor Freight "wobble" short (3" +/-) extension and had no trouble reaching the fill plug...piece of cake! Used a longer extension to reach the drain...again a wobble & little or no damage to the cooling fins.

As #27 stated, both plugs from the factory are surprisingly loose....maybe finger tight. Mine had the same amout of debris as those shown by other posters. I used the $5 pump as seen in Post #35. It's easy to fill - I just rested the top of the pump against the bottom of the muffler and kept pushing the bottle up & down to work the pump...little tedious but a clean fill compared to past experiences.

I also had the same question as Post #35 about whether it was actually full. I took out 2 (factory-fill) quarts and put in 3. Note mine is not eLSD, and only supposed to take 2.5 quarts. If anyone had doubts about changing this fluid, the fact that the factory fill seems to be short according to several posts, the plugs are loose, and the old fluid coming out is filthy, should convince you to do it or get it done by the dealer.

As Post #41 asked, Why change? One picture is worth a 1000 words!

Maxie2U

I’m now convinced I need to change mine. Currently @9845 miles.

Thank you

iclick

I changed the gearbox fluid in my GS last summer using the stock Delco fluid and it went mostly as described by the OP. The GS's large rear sway bar and cooler lines that block access to the fill plug was more of a problem than in my 2015 that didn't have a sway bar, and a flex wrench is a must.

I did the M7 change yesterday and have some suggestions to make. After reading this thread and doing further research I decided on the D4 fluid, buying a gallon jug from Amazon for $48 shipped. That's about 2½X the cost of the stock ATF, but since I'll likely only need to do this change one time on this car and having an expectation of smoother performance I decided it was worth the $25 cost increase. Seeing some photos in another thread of how the ATF tends to fly everywhere when drained, I decided to make an attempt to restrict its flow by wrapping areas around the drain hole with aluminum foil. I also cut a 12x12" piece of cardboard to protect my face from the fluid, and both ideas turned out to be worthwhile. It is low viscosity, about like water, so flow is much faster than motor oil or gearbox fluid. It took just short of the full gallon jug to fill the M7.

The D4 fluid smells awful, much more obnoxious than the stock fluid, and you will want to keep it away from everything except the inside of the tranny. I wore latex gloves and tried to keep the stuff off of me, which was largely a failure despite the efforts. The old shirt I wore ended up in the trash bin outside. Some will end up on you and your clothes, so wear clothes you don't value for this job.

I used a fluid pump from HFT (#63114) and it worked well except for one caveat. The tube that enters the jug of fluid is curved and I had to tape a dowel to it to straighten it out so the opening would access the bottom of the jug and extract all the fluid.

I can report after two drives, one this morning when cold, that shifting is smoother, especially when cold. I didn't feel the slight 1-2 grind as much, mostly none at all, when cold that I had become accustomed to before. Overall, I think the decision to use D4 fluid was the correct one.

Kracka

Glad you are happy, and thank you for the additional tips! I too ruined a shirt this last time

Bruce_K

i did mines as well i tried to video the whole thing. I havent had any issues with it yet!

rv3flyr

As expected, the oil change in my M7 was uneventful, thanks to the comments/methods mentioned here. Unfortunately, while draining the tranny, an unnoticed and significant amount of the old fluid found its way into the rectangular suspension housing directly aft of the tranny, through a couple of holes in the forward side. As I was backing out of my garage and and driving away, I left a perfect stream of transmission fluid all across my driveway pavers, as it leaked out of the housing as I turned. Moral of the story....... if you're as picky as I am about your driveway, be sure and flush out all of the accumulated fluid from the housing before departure!

iclick

As an update to my earlier post (#66), after about 10 days I must mitigate my description of any performance improvements--i.e., smoother shifting. I would now say that any improvements over the stock fluid are minimal or non-existent and I wouldn't recommend changing to Redline D4 and possibly any other higher-priced fluid on this basis alone. It might be that a synthetic is more durable, both for the fluid and the mechanicals, and that might make it worthwhile--but if I were to do it again I would probably just do the change with the stock fluid, which is economical and probably works as well as any for its intended purpose.

See #66 above about using aluminum foil to channel the oil as it drains. It worked well and I didn't get any residual oil on the surrounding housing or frame parts.

Kracka

What changed from your initial impression? I would be curious to see you go back to the OEM fluid and hear your back-to-back comparison again.

rv3flyr

I agree. Still a little notchy, and still an occasional little crunch from 1st to 2nd. I couldn't tell any change at all.

dbaker

FWIW...I changed my M7 fluid at 700 mi.One thing I did notice,it seemed to be approx. 1/2 qt low from the factory and very silver/red.

I'm not sure if the change improved the shifting or just the fact that it was low.3.3 qts out & 3.9 qts in.

\db2

iclick

The impressions given in my first post after changing the fluid was based on two drives, one after the change and not completely cooled down and a second the next morning. It did seem to help with the notchiness, but I can't say that after more test drives.

Former USMC

Kracka,

Nice write up - thanks. I too, did the exact same thing (well sort of). I replaced my transmission fluid with Redline and rear differential with GM differential fluid with posi-traction additives. I had the dealer do the fluid replacement - a bit pricey, but worth it. My fluid for the transmission and their fluid for the differential. My Z51 had ~20,000 miles.

Upon leaving the dealer, I found a cut-de-sac to do several figure eights in both directions. It was my understanding this was a proper technique after replacing the differential fluid.

I also noticed the transmission easier to shift after replacing the fluid with Redline synthetic. Especially that first 1st to 2nd shift when cold/cool.

I also contacted Tremec, Redline and the GM service tech and all three said Redline synthetic is fine for the C7 manual transmission.

Take care and again, nice write up.

Semper Fi

RapidC84B

Do you need thread sealant on the drain plugs like with the C5s? Or, are there crush washers on the C7?

Kracka

There is sealant on the threads; I have not added any additional and simply have reused it as-is after both changes.

RapidC84B

Kracka

Smart idea! I'll likely add a little next time.

RapidC84B