For new vehicles, I think it's a good idea to service all fluids early, one time, after the first few thousand miles. This will remove most of the wear-in particles and promote (not guarantee) a long and trouble-free service life. Then after the early change, follow the manufacturer's recommendations. Often the manufacturer will not recommend changing a fluid, ever... I have seen this no-service recommendation with some differentials and transmissions, and usually under "normal service" conditions. (My 1995 Corvette is a good example, .) Despite this recommendation from the manufacturer, it's still a good idea to change fluids periodically. I'd say *approximately* 50k for manual and automatic transmissions, about 75k for differentials, and about 100k for power steering and coolant.
Here's a page from the owner's manual of my Corvette which says, "Manual transmission fluid doesn't require change."
![[Linked Image]](https://www.bobistheoilguy.com/forums/attachments/usergals/2019/10/full-39486-37024-7_30.png.jpg "[Linked Image]")
The differential section shows what kind of fluid to use and how to top it off, but there's literally nothing about changing the diff fluid. Maybe because *the differential has no drain plug* on this car. Ridiculous GM.
Here's a page from the owner's manual of my Corvette which says, "Manual transmission fluid doesn't require change."
The differential section shows what kind of fluid to use and how to top it off, but there's literally nothing about changing the diff fluid. Maybe because *the differential has no drain plug* on this car. Ridiculous GM.
