99 S70 AWD Tranny Fluid Pattern

[hookladder]

I have a 99 S70 AWD that I purchased @ 37K. At 37.8K, the vibration from the tranny downshifting from 4th to 3rd (approx 55 mph) got pretty annoying (LOUD vibration throughout whole car, almost like a big chunk) so I finally made a repair appt. They had the car 3 times within a month and never fixed or "experienced" the problem. Finally they found a bulletin on their system that recommended to change the tranny fluid. That solved the problem. BUT.... I'm at 52K now, same deal. I have it in the shop right now as I type. Just talked to the service mgr, he says that the tranny fluid is black as night. I see a pattern emerging... but how many times can the tranny grind down (if that is what is happening) before the gears are gone? Is there anyone who knows/experiences the same thing? I mean the warranty is still there, but I would love to keep the car longer than 75K (which at this rate seems like a wise mileage to get rid of it). Anyone?

[MJJ]

Don't know about the noises but I can say that when I changed the ATF at only 18K it looked like some fine French Roast. Something about these trannies. I think it's wise to add the ATF change to the yearly maintenance list. Maybe they use ATF rather than engine oil to cool/lube the turbo?