Was it motor oil or ATF? When ATF is burned, or dark brown in color, its a bad sign for transmission health. It normally means that clutches have been slipping. Whatever else you do, you need to make absolutely certain that the transmission is purged completely of motor oil if you switch to Dexron III. Dexron III is not compatible with motor oil. When I switched to Dexron III with the drain and flush technique, I was happy that I did it myself because I was certain that I did it right. Also make certain that if you switch you only switch to Dexron III. Later versions of Dexron ATF are not compatible with some of the o-rings and seals in the transmission.When I drained the oil the first time, it seemed to be pure ATF (albeit burned). Is there a good way to clean the system without draining multiple and filling times?