So I just got all the parts to rebuild my 90 3sp 727. I am rebuilding the internals this week. I need all fresh fluid. But, Mopar ATF is pricey. I have access to free Dexron GM auto transmission.

Does anyone know if it is okay to run GM's Dexron in the 727?

 

I've been told by my trusted auto parts guy
that Valvoline Max Life Dex/Merc ATF is
really ATF +4.
He explained that they couldn't put that
classification on the bottle for
marketing brand reasons.

 

All dextron type trans fluids were made to interchange. If your trans was made for straight ATF. Atf-4 will not harm it.

Fill it with your choice of fluid.

 

You add a friction modifier to Dexron to make ATF+4.

When I've put money into a transmission, the price of AmZoil ATF fluid seemed quite small. That said, if it had to be drained for service, the fluid was salvaged and returned to the transmission.

 

I have to agree with John on this one (as with most of his inputs). You have spent a considerable sum of money to buy the parts for the rebuild, don't you want to use a high quality, proper fluid to protect your investment and insure it's longevity?

As always, YMMV

Cheers!

Mike

 

ATF+4 is a synthetic fluid. Just adding a friction modifier to regular Dexron does not make it ATF+4.

Since your 727 is a non lockup you can run just about any fluid you want in it, even some tractor hydraulic oils would be fine. The regular mineral oils would need to be changed more often as they don't stand up to heat as well as the synthetics. The choice is yours.

 

I think the later dexrons are synthetic. At any rate, the friction modifier additive in dexron is considered a stop gap measure. I carry a small bottle of it so if I get into a situation on the road, like a blown cooler line, where I need to top off the fluid and ATF+4 isn't available, I don't have to worry about gumming up or burning the clutches.

The A518, which is basically a 727 with an OD tail assembly, requires ATF+4 to run properly.

As I said. It's expensive to fix any of these transmissions, so I run top shelf fluid in them. I just got back from a fast run out West, with many miles of full bore pull, or hard engine braking with the A518. Engine and tranny ran flawlessly under punitive use.

 

Supertech ATF+4 is what I use . 4.25 a quart. Works for me, and u can get at any walmart