Sae 10w or dexron 3

[Soaringcook]

I'm about to change my tranny fluid, it's a mt643

But I cannot tell if I have 10w motor oil or old dexron 3.

The oil looks brown clear.
And I know that old dexron can turn brown.

Any help will be appreciated.

I attached a pic

[s2mikon]

It more than likely had 15w40. It was listed as an approved fluid for years. I've used it in units myself.

[Soaringcook]

I just got a hold of the maintenance records and it looks like they used Transynd 295. I guess it turns golden after the while

[Booyah45828]

Check with smell. Trans fluid and motor oil have different smells.

And a fluid drain/fill will typically retain a brown color afterwards from the leftover fluid not swapped out of the unit. So color really doesn't tell much.