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4l80 transmission

THEFERMANATOR

FRANKENBURBAN
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No evidence to suggest DEX VI is harmful to seals. It's been widely used for years with many having no issues.
Except for there fluid engineer that went to work for Allison admitted GM knew dex vi was NOT reverse compatible with older rubber/neoprene seals hence why he wrote the bulletin that Allison released regarding the S/N breakpoints regarding the switch to viton seals. It's quite obvious you've made up your mind on it, but you cannot change my mind as I have seen 1st hand the damage that dex vi has done to older seals, talked with other shoos who seen it, and read what the fluid engineer wrote in regards to it.

GM only came out with dex vi because the patent on dex iii was expiring. So they switched to a synthetic fluid of a thinner viscosity. And considering how much trouble most of these transmissions experience with fluid leaking past bushings due to uncoated bushings, why chance it with an even thinner fluid.
 

Will L.

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Right, worn bushings are not a reason to blame a fluid. But if there is another fluid that will help that issue, and one that won’t, something to consider.

Just like power steering system. You can run the power steering fluid and it works fine. Then as the system wears you can rebuild components to stop the leaks. Or, you can run dex3 from day one and the system will last the same miles, except when the amount of wear that would allow leaking will continue to operate without leaking and thereby effectively extend the useable life before having to repair. This of course yields lower cost of ownership. Especially for those who run rigs to the half million mile point, eliminating 1 entire repair cycle. This was a hot topic in a huge fleet of 6.5 gmt400 trucks I signed my name on for an oil & fuel company, who btw did oodles of testing for GM. The oil company obviously wanted a second line of oils out there and worked hard at pushing out atf from the ps system. Why when it is a reliable fluid that costs less and gives lower cost of ownership to the end user? Oh, because the oil company makes more profit, simple.

So, why on earth would GM want to switch to a different fluid from one that many, many people run in the trans for hundreds of thousands of miles? How robust- knowing the downtime of a trans swap was more than cost of a trans and we tended to out the trucks by 300,000 miles - we had, in the time I worked there, hundreds if not over a thousand trucks break the 300,000 mile mark and they NEVER ONCE got a trans filter and fluid change. Most of These trucks were drove HARD. Drivers that made better money by blasting over curbs at 20 mph. When we did oil changes, the driver sat in the seat and handed the keys out the window. Shoft change had the engine not shut off for 70% of the fleet. Remember I said most trucks replaced? Some are still there. They are down to 4 trucks still running their schedule and trying to record total cost of ownership for the 5,000,000 mile mark. They tried dex6, talking with the dispatcher is where I learned the issues with dex6 vs dex3.
Dude. I am telling you. Dex6 DOES NOT handle it the same. Maybe fault of a bushing. Maybe fault of a seal. Maybe fault of a truck driving over an ancient Indian burial ground. DOES NOT MATTER. DOES NOT HANDLE IT THE SAME.

I think, anyone who read this thread to this point gets the opinion of all involved. They can draw their own conclusions.
Here is the bat, the dead horse is only a red carpet of horse hair left, but by all means - do continue if you wish. Maybe your personal guarantee of paying the difference in cash will convince any fence sitters left.
 

THEFERMANATOR

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If one has worn bushings (not a seal) that is something not related to fluid. Like I said there are a hell of a lot of folks that have switched fluid in a 4L80E and have no issues.
I NEVER said worn bushings, I said fluid leaking past bushings because they were uncoated. At the same time GM switched to dex vi, they also started using coatings on the bushings to tighten tolerances and reduce inherent fluid bypass.
 

Stoney

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Ok a little off topic..@Will L said something I'm not sure if I read correctly..did you say to run dex/Merc in power steering instead of power steering fluid? Or did I read that wrong?. Asking cause I've replaced pretty much the whole power steering system and it still ain't never worked consistently right..kind of hit or miss....as for dex Merc vs. dex vi. Ain't no way I'm risking it..I got almost 300,000 miles on this truck, and it still runs..not changing now... personal I'm not tranny expert..but I trust @THEFERMANATOR and @Will L. And a few other guys on here that I know seriously know there shit...I take there word as GOSSPIL.
 

MrMarty51

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Used to be that Dexron trans fluid was all that there was. I dont onow when PS fluid came about.
I dont know about this real new stuff but, the older units, maybe up to about 2005, I think can be switched over to Dexron ATF. I wouldnt use ford type ATF though.
Maybe @THEFERMANATOR or @Will L. would know the answer.
 

Will L.

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I don’t remember when straight poser steering fluid came out for GM, I must have slept too much since then.
But I can’t remember a time GM made a ps system that couldn’t run dex3. I remember it was approved for my 69 Camaro. Miss that car once in a while. Don’t miss buying rear tires every couple months though! Haha.

I ran dex3 in my 65 and 66 truck ps. I don’t think it was approved but it worked well.
 

THEFERMANATOR

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I normally use dex/merc fluid in all saginaw pumps. I wouldn't use it in the newer electric systems though. I had been running royal purple max ez power steering fluid in mine. It is rated to stupid high temps(can't remember what it was right now) and is of a thicker viscosity designed specifically for off road and race use. It's not cheap, but it's good stuff.
 
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