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Anybody running synthetic in their 4L80E trans?


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My '01 2500 Suburban with 8.1 and 4L80E trans is due for another fluid change. I change every year, and am now at 56,000 miles and considering switching to synthetic. Buddy just bought a complete flush machine for his shop, so can now get a complete purge and not just a drain/fill.

 

I like to change all fluids every spring before towing season with 9000 lb RV. Tranny runs fairly cool now, about 150 degrees empty, and about 175 towing, but will climb into the 200-210 range if pulling a long hill with the trailer. Not really concerned about extended fluid change intervals with synthetic, but would like to see lower temps while towing.

 

I have generally heard all around good things about synthetic, but am wondering if any downside to changing at this tim, or in thsi tranny, or for any other reason. Comments please....

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From a performance standpoint, Synthetic transmission fluids are absolutely HORRIBLE and are the cause for many failures.

I have personally had a TH700R4 fail due to Mobile 1 ATF, and I know about a dozen more who have experienced the same fate with their transmissions as a result of using M1.

The technology in M1 fluids is great, however unlike engine oil, transmission fluid should NOT be that slippery. In my built 700R4, I run standard Dextron III ATF, 2 Quarts of Type F ATF (Ford trans fluid has better friction modifiers) and 1 bottle of LubeGuard Red (to stabilize the transfluid and keep moving parts from sticking).

Mobile 1 ATF seems to lack these friction modifiers and as a result, causes premature failure to clutches and bands.

 

Now again, Im no expert and the only experience I have with this is from a performance standpoint which may not result the same as it would in a heavy duty/towing application but I just wanted to throw the information out there to be pondered, take it as you wish.

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I've used M1 ATF (DEXIII spec.) in all automatics I've owned and have never had a problem. Changed one trans over to it at 120,000 miles. It now has 154,000 on it and it shifts like new. I also use it in transfer cases that spec DEXIII and plan to use it in my new Allsion 1000.

 

I am very surprised by NJTy180's comments. He's the first I've ever heard that had a bad experience with it.

 

If it meets GM's spec for the 4L80, they should be an improvement.

 

NJTy180 : How long ago did these failure(s) occur?

 

DEWFPO

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"I'm surprised there's so much conflicting info on synthetics"

 

I think if you do a search on this forum and others, I think you'll find that problems with synthetics are indeed rare.

 

DEWFPO

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I've used M1 ATF (DEXIII spec.) in all automatics I've owned and have never had a problem.  Changed one trans over to it at 120,000 miles. It now has 154,000 on it and it shifts like new.  I also use it in transfer cases that spec DEXIII and plan to use it in my new Allsion 1000.

 

I am very surprised by NJTy180's comments.  He's the first I've ever heard that had a bad experience with it.

 

If it meets GM's spec for the 4L80, they should be an improvement.

 

NJTy180 :  How long ago did these failure(s) occur?

 

DEWFPO

 

 

 

my trans problems that occured with M1 happened late 2001 early 2002.

 

Meeting the specs doesnt really mean anything. Mobile 1 Syn motor oil meets the same specs as conventional motor oil, I would surely home the same would be true for transmission fluid.

 

If youre interested in checking out opinions on different forums, here's another link for ya http://www.syty.net/forums/showthread.php?t=15691 There are some people who havent had issues with it on there too, or at least back when that thread was made, but either way mine is not an isolated incident nor does it seem "rare" and its pretty much a general rule over on syty.net to warn people about the problems with using Mobile 1.

 

Either way like I stated earlier, my only experience with it is performance based, prehaps these issues dont occur with transmissions that are built to make hard positive shifts, i dunno I was just throwing out another option, Id hate to see someone blow a trans from using s**tty fluid and I know personally I will never use Mobile 1 ATF in any vehicle I ever own.

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I've got a 93 Suburban with a 4L80E and I use Amsoil full synthetic. Works great. I have towed my camper quite a bit (Rockies, etc). I break open my pan filter every year to check for shavings. Despite running it hot (due to blower), works like a champ. During summer of 2003 a tranny line ruptured along the interstate, somewhere in nowhere Ohio. Eneded up gettting it topped off with regular dexron. Big difference in smell and color, after some hot towing.

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