Greetings. My question is, Is there a replacement trans fluid I can use for the 99 Mirage ATX that won't ruin the ATX. The manual says SP II. I know the SPIII will work but i'm trying to avoid the dealer. I realize it is a proprietary fluid (Dealer only). Thanks.

I went around and around on this issue a couple of years ago when I first changed the fluid in my daughter's '00 Mirage. After much research and many emails to the tech departments at the various manufacturers, I decided to stick to the dealer only Diamond SP. While the universal fluid that some sell is supposed to be compatible, I think it's taking too much of a chance for too little savings with something as expensive as a tranny. Apparently the SP fluid has certain specific anti-friction additives which are required by the trannies used in the Mirage.
FWIW
YMMV

Thanks DFBONNET.
You confirmed what I had pretty much researched. My daughter bought the 99 and the tranny fluid and two filters need to be changed. It has 115000 mi on it and it doesn't look like it's been done in a long while. I guess thats what dads are for.