Hey guys.
I wanted to drain my trans and fill with some nice mt-90 but found the old fluid was super dirty, so I tried to run some cheapo gear oil for a mile or two and flush again to make sure i got all the funk out. When I went to drain the cheap oil though it came out all foamy or bubbly like champagne or foamy beer. THe bubbles seem to rise and settle out in the jar i put some in. Whats going on here??? It shouldnt be water, cause its fresh fluid and the original stuff wasnt foamy like this (though the truck had been sitting for the evening for the first drain). Im pretty sure I didnt over fill. Is it the type or quality of the oil?

Do I fill with mt-90 and run it? Or will it do the same and ruin my $70 gallon of trans fluid?

Thanks all.

 

Gear oil just like engine oil should be drained warm.

Then maybe you drain the engine oil cold.



No telling what kind of water was in the neglected gear oil. As things cool the water and gear oil and solids separate .

I can only think the short trip was not long enough to get things warm enough so all the water and left over slop could mix.

Just what cheap gear oil did you use ??

 

Well... Even if it didn't mix with water or other contaminates at the molecular level it should have stirred up enough to remove it with the see second drainingright? Ie the trans might be good to go with the next fill?

Original gear oil is unknown. Truck is new to me recently. Cheap gear oil was Masterpro 80w-90 gl-5 from Oriellys. I know gl-5s aren't the best for this transmissiin but figured it would be OK to use for a flush right? Could the two oiksv have reacted or something?