hypothetically if you bought a 100k mileage evo and you arent sure if the rear diff fluids were changed, would you? or would you stick to the old school theory of not changing old fluids on a worn out diff?

test drive indicates no abnormal whine from the rear of the car...

 

drain the fluid and have a look see

 

I never heard of that old school theory and I'm definitely old school - more like ancient school.

 

well i dont 100% buy it but there is this debatable idea if a diff or transmission with old fluid, it often needs the gritty shavings to keep from slipping...

just an old car theory like 3k mile oil change too

 

I say just change it, then keep up with the maintenance. No reason to leave old fluid in there just because you "think" its never been changed, and end up really ruining it.

Aaron

 

Ahhh, the oil is too clean theory. One of my favorites.