I'm way beyond tired of adding $5 qts of mobil-1 all the time, or driving my car with not enough oil in it. I know for a fact that I wouldn't consume even remotely close to the amount I do now if I were running regular instead of synthetic. Has anyone switched back and had any problems? I know it's not good to switch between types of oils, but my engine theory professor claims it's ok to switch as long as you aren't going back and forth. I also hear that some rubber seals can go bad if you've been running synthetic for a while and then switch to regular. Has anyone switched from synthetic back to regular and had any problems? Does anybody (that has experience in the matter, or knows what they are talking about) have any advice on this?