30k miles is probably ideal. Seems that if you go longer than 50 you may as well not change it. I know several people who have changed fluid and filters after 70k-100k miles and experienced transmission failure around 2 weeks later.

I know it's kind of messy and everything, but c'mon changing the fluid is alot easier than rebuilding a it. Not to mention cheaper...

 

I changed mine in the S-10 for the first time in 150,000. And now the starter goes out!

I'm thinking the next time the fluid gets changed, I'll get it flushed with Amsoil.

 

Why didn't you just put it in when you got the new tranny? I have amsoil in everything but the block.

 

Because my dad forgot to tell him that when he called him. Same thing happened when i asked about a shift kit.