Is it bad if I had 80w-90 gear oil in my transaxle? I replaced it with 10w-30 last week. I’m not sure how long it was in there but it looked somewhat burnt.
I wouldn’t worry. Everything I’ve heard backs up the idea that gear oil and standard engine oil viscosity ratings are actually completely different. Sounds like the stuff you used is 3 times as thick as the engine oil, but that’s not really the case.
There is probably a better chart out there, but I found this really quick on google, if you want to look into it more I’d spend some time googling. http://www.aimag.com/forums/harley-oil-lubrication/3152-hey-bluesfan-gear-lube-viscosity-vs-motor-oil.html
Trans fluid is gonna smell a bit nasty no matter what. Also, the Honda MTF I recently put into my new trans looks thinner than your standard 10w30. Not sure what it specifically is. Personally I like to use Honda MTF or GM Synchromesh in my transmissions.