Almost put this in the tranny section, but that section doesn't seem to get too many hits. Mods, feel free to move as you see fit.

Got a C6 behind an IDI. Tranny fluid smells fine, and is completely transparent. One issue: It looks like new motor oil.

I stretched the Google skills a little bit, and I came across a few brands of tranny fluid that are gold cold - Castrol Transmax J and Penosin fluid, specifically. But they're spec'd for Subaru, BMW, Benz, Volvo, etc. Definitely not an '85 C6 that calls for Dextron III!

Anyone ever hear of Ford-compatible ATF that isn't red? I'd almost expect the PO to have gotten the tranny fluid changed at the most sketchy of sketchy shops, but I'm not sure there's Dex/Merc so cheap now-a-days they don't even add DYE to it.

I'm planning a drain and fill here, maybe tomorrow, but I found a couple bottles of Mercon V in the cab when I bought the rig, so I'm not sure what to do. I heard Merc V has been reformulated to work in Dex/Merc spec transmissions - Considering that, figure an incremental drain 'n fill to remove all the old fluid would be okay, even if it happened to be filled with Mercon V before?

 

Drain it. And you should be able to turn the engine around by hand till a plug comes around to the bottom where the flywheel cover is located(take the cover off). When you do this, you can get ALL the old fluid out by pulling the tranny pan and taking the drain out of the torque converter. It will take around 13 quarts or so to refill it.

It originally took Dexron, I don't know what they call it now. They also have a Dexron, I believe it's 6, that is a synthetic blend you can use, but it's a bit more expensive. The cheapest place to get it is Walmart in their "Tech" brand.

 

Dex/Merc is the new name for the old Dex. You can run Merc V, but as noted, more expensive.