So I got a 5 speed yesterday for my swap and it's been sitting for a few years. Has a bit of water in it from condensation. I was planning to just fill it with ATF and run it for a few hundred miles before I change to gear oil.

 

Is this a dumb idea? Anybody have better suggestions that don't require me to tear into it?

I would just drain it, add a gallon or two of diesel, slosh it around for a while and then refill with the proper gear lube. No way I would run ATF. Hard to believe anything could be wrong if it had been stored with gear lube.

I have no reason to think anything is wrong with it. I can turn the input shaft by hand without much effort and the outputs turn. I just want it to be clean so the new gear oil doesn't get fouled up. The diesel sounds a bit easier.

 

Thanks for the input.