2012 M6 Transmission fluid change?
Thread Starter
Safety Car
Joined: Oct 2002
Posts: 4,277
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From: Austin Texas
2018 C6 of Year Finalist
2012 M6 Transmission fluid change?
Changing my transmission fluid on my 2012 dry sump ls3 M6 with 14,000 miles today. Drained it last night and the fluid was red. What is the factory fill fluid? I am changing over to Royal Purple Synchromax. Members how have used it what are your opinions?
Thanks, Michael
Thanks, Michael
Pro
Joined: Sep 2013
Posts: 644
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From: Metro Detroit
Factory fill is Dexron III ATF. I and many others have used RP Synchromax with success. It is the fluid that RPM Transmissions recommends, FWIW. Some don't like it, however. It is thicker, and can make cold shifting slightly more notchy, but once warm, it shifts like butter. Since you already have it, you might as well try it and see what you think. If you don't like it, you can always switch back to ATF.
Safety Car
Joined: Nov 2006
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I have Redline D4 in my 2011 GS MN6 currently, and it did feel a little smoother.
Surprisingly, my fluid temps went up (as monitored with my DashLogic device, over the OEM Dextron fluid. Not by much, but it now gets up to about 200 during my 30 minute drive to work thru Daytona, and it used to only get to about 190.
No biggie as far as I'm concerned. I'll watch it next track day to see the real temp swing
Surprisingly, my fluid temps went up (as monitored with my DashLogic device, over the OEM Dextron fluid. Not by much, but it now gets up to about 200 during my 30 minute drive to work thru Daytona, and it used to only get to about 190.
No biggie as far as I'm concerned. I'll watch it next track day to see the real temp swing
Thread Starter
Safety Car
Joined: Oct 2002
Posts: 4,277
Likes: 161
From: Austin Texas
2018 C6 of Year Finalist
Interesting. Did not realize Redline D4 was preferred over RP Syncromax on the forum. Might have to return the RP and buy some Redline.
I have Redline D4 in my 2011 GS MN6 currently, and it did feel a little smoother.
Surprisingly, my fluid temps went up (as monitored with my DashLogic device, over the OEM Dextron fluid. Not by much, but it now gets up to about 200 during my 30 minute drive to work thru Daytona, and it used to only get to about 190.
No biggie as far as I'm concerned. I'll watch it next track day to see the real temp swing
Surprisingly, my fluid temps went up (as monitored with my DashLogic device, over the OEM Dextron fluid. Not by much, but it now gets up to about 200 during my 30 minute drive to work thru Daytona, and it used to only get to about 190.
No biggie as far as I'm concerned. I'll watch it next track day to see the real temp swing
Thread Starter
Safety Car
Joined: Oct 2002
Posts: 4,277
Likes: 161
From: Austin Texas
2018 C6 of Year Finalist
Just got through draining and installing the Redline D4. Only held a little over 3 quarts before it started flowing back out the fill hole. Thought it held 3.5 quarts. Any thoughts? Do I need to go for a drive then top it off?
Race Director
Joined: May 2004
Posts: 16,667
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From: Raleigh, NC
St. Jude Donor '15
If it came out the fill hole then it's fine. Manuals are much less sensitive to fluid level.
I drove mine around 2 quarts low for months and it was fine (and is still fine) at 170K miles, so no worries.
The exact amount it takes is going to vary a little based on how long you let it drain, angle of the car, etc.
I drove mine around 2 quarts low for months and it was fine (and is still fine) at 170K miles, so no worries.
The exact amount it takes is going to vary a little based on how long you let it drain, angle of the car, etc.
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To the OP, do not make the mistake of using a DEXRON VI ATF as it is too thin.
Thread Starter
Safety Car
Joined: Oct 2002
Posts: 4,277
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From: Austin Texas
2018 C6 of Year Finalist
No I do not track my car. Glade I changed it. The shop that installed my clutch left it a quart and a half low. I Was thinking it was the cause of my trans not going into reverse issue. The problem ended up being that my MGW shifter was out of alignment. 
Melting Slicks
Joined: Nov 2010
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From: On the east coast we drive until we die
I have an older version of Amsoil's ATF in my manual C6 and it says it's compatible with GM II, III, AND VI. But it doesn't say what spec it is. Only that it's compatible with these 3 offered as factory GM fill.
Race Director
Joined: Sep 2000
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From: Missouri City, TX
That older version of AMSOIL ATF will be perfectly fine. I used it in my 06Z06 for 10s of thousands of miles. AMSOIL has a different ATF product that is for DEXRON-6 specs for auto trannies.
Melting Slicks
Joined: Nov 2010
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From: On the east coast we drive until we die
5th Gear
Joined: Mar 2015
Posts: 5
Likes: 0
From: Kingsburg California
Just changed my 2005 C6 manual with 3.5 quarts BG Synchro Shift II from Zip, much thicker fluid than the factory fill ATF? that came out. Car has 50,000 mile and is new to me, don't know how it was driven, so I changed the fluid. Seems to shift smoother now. No problems on cold morning, but just how cold does it get in Central Calif?