I got a good deal on some motul 75w 140wt gear oil I was planning on using on my 87 t2 rear end and transmission. Is that too thick?

 

I wouldn't say so, considering you live in Pasadena. Now if you lived in Colorado, that'd be a different story.

 

cool, thanks

 

140 is WAY thicker than 90. I'd definitely stick with 90 weight unless you're seeing some seriously high temps in the diff and tranny.

 

It probably won't hurt anything using a thicker 140, but you will have increased driveline power loss, which means your car will not be as fast.

 

... and will probably get worse gas mileage.

 

doh! Maybe I'll return it, thanks!

 

My father always tells me this story when I justify using cheap *** high viscosity oil in my cars that leak.

He had a Saab once that leaked transmission oil. So one day he decided to replace the 90wt with 140 wt oil.

He said it'd move forward in Neutral if he didn't push on the brakes. He put the right oil in afterward.

 

use the factory recommended weight.