I maintain my AT's by draining and refilling ever so often. I simply drain out 2-3 quarts, whatever comes out by gravity and then refill with the same amount. I'm using Amsoil transmission lubes and am wondering how often you think I should do this? Every 10K, 20K, 30K,?

 

The owner's manual specifies the change interval.

 

Since the quantity is so low to refill, I try to do it at the same time engine oil is changed.

 

I think this always is a good question and always a hotly debated topic. For me personally I'm in the boat of...change it regularly. I own a 460 and it has a "lifetime fluid" in it, but I don't believe that and neither do most techs, so I change it every 50,000 miles. So far so good.

Another example would be a Honda Accord I owned that was notorious for transmission failures - the recommended change intervals on that car were every 20k miles...which I did...and to my surprise it still is operating properly at 286,000 miles. That is unheard of for that transmission as most fail at around 100k miles. I believe the maintenance was key in its longevity, but the way you drive also plays a huge roll.

As for the question above...it depends on your car and how you drive. I also would only use whatever fluid the vehicle calls for. But let's say you live in an area that is hot - well heat breaks down transmission fluid - and if you pull or tow anything, heat will break down that fluid faster. So changing it sooner than recommended would be in order. I'd say simple drain and fills at 20k miles would be fine....perhaps over doing it a bit, but fine. I think drain and fills every 10k miles are a waste unless you race or tow a boat.