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Hello. I have a 2017 LT with a 1.5 and 6 speed transmission. I am coming up on 40,000 miles and wanted to have transmission service performed. I had an expired coupon for 149.95 and called my dealer to schedule assuming there would be a new coupon or it would be a bit more expensive. I was thinking $200. The dealer quoted me $500! The said they had a machine that changed all the fluid and it only took 30 min but now they have to do a manual drain and fill twice and they need the car 4 hours and no loaners are offered. I have to pass on that.

I need to learn to do this myself. I already bought 10 quarts of ACDelco full synthetic dexron 6 hoping to drain and fill twice. I have a 6 quart drain pan with measure. I see the metal plug under it is on the bottom of the unit toward the front and sticks out a bit. The fill is a black cap in a hard to reach spot between the battery and the ECM. I have three questions:

Are these the correct fill and drain spots?
I don't think my hands are small enough to reach that fill cap. Do I need to remove the battery or at least the big box that contains the positive clamp?
Do I do this hot or cold? The instructions I have found don't specify. Some emphatically say cold only. But then I think, how would the dealer ever do it cold?

Any thoughts are appreciated.
 

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2016 Malibu 1LT 1.5T
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Are these the correct fill and drain spots?
Yes.
Do I need to remove the battery or at least the big box that contains the positive clamp?
I did. I could get my hand on the cap but I couldn't twist it. I had to pull the negative and pop off the positive the first time. Still not much room but doable. After doing it once I was able to just reach in there and twist - it was just stuck the first time. If you do remove the negative or whole battery, be careful; wait 10 minutes after powering off the car. Your onstar system has a backup battery and if you pull the negative while retained accessory power is on you drain the battery and get a red light on your onstar console.
Do I do this hot or cold?
Cold. The manual specifies a temp for checking the fluid level but not the drain and fill. From a common sense standpoint, the dealer will do it somewhat warm so that can't hurt it's just less effective. The concern is at a certain temp a valve seals fluid in the valve body so if hot you don't get as much out. I got about 4.5-5 quarts out of mine cold. Just put back in what you get out. I made a guide for it a year ago... it has stayed a work in progress for a long time but here it is: How-To: 6-speed 6T40 transmission drain and fill gen9...

If you want to verify the fluid level, you have to heat the fluid to 85-95C checking with a scan tool. In my case, I drove around until I got it to 90 then had to use 2nd gear to push it to 95C. I went a little extra knowing it would take me time to position and jack the car. With the engine running, I put the back on ramps, jacked up the front, then there is a plug on the driver's side of the transmission. I waited for the temp to settle at 90C. Open and if fluid just drips out you are all good. If it pours, it should go to a drip. If nothing comes out, you have a problem and have to get more fluid in there which would mean a lot more work.

If my ramble gets confusing, just message me and I can send you some clarity.
 
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I did two drain and fills separated by 50 miles of driving. I did have to pull the battery positive cable out of the way. On the 2nd drain and fill I added an extra half quart. I then drove it to hot and used my ODBLink bluetooth dongle and torque app and got the TFT 100 then jacked it all up and checked once back at 90. I let about 1/4 quart drain out the check plug until it just dripped. I have driven it about 75 miles since the 2nd drain and fill and man, what a nice difference. I had some slow maybe even jerky shifts from 2nd to 3rd and some shudder from 5 to 6 before and that is totally smooth now. I am not sure if it is the extra 1/4 quart and now being at the right level or going from the factory dex6 to full synthetic acdelco dex6 but I think it was 3 hours well spent. Thanks again for your help.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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I will hazard a guess that it's a combination of 3 things, from most to least:
  1. New fluid
  2. Full synthetic instead of blended
  3. ¼ quart of extra fluid
The new fluid will replace dirty fluid, which tends to gum things up in the smallest passages. The synthetic is more stable over a wider range of temperatures and flows better when cold. The little bit of extra fluid probably didn't make much of a difference, if any, but it didn't hurt.

A couple years ago I did several drain-and-fills on my 2011 V6 6-speed using full synthetic fluid. The first was 10,ooo miles after getting the engine replaced under warranty. When I drained the fluid and reinstalled the same amount, my 1-2 shifts were dicey under heavy throttle but all others were fine. I finally lit upon the idea of checking the fluid level and added 3 more quarts. The 1-2 shift was no longer an issue. The shifts also felt better, but that may have just been my bias of knowing that I was using better fluid.

About 20,ooo miles later I did another drain-and-fill. Again, the shifts felt a little better, but it could still have been the same bias.

I've done it twice since just to raise the average age of the fluid to above 90%.
 
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