My 1999 Saturn does not use any oil. My 1993 goes through a quart every 500 miles. I put dye in the oil and checked for leaks but did not find any yet, but my mechanic said we should look again in a few days. (There is a wet patch in my driveway) Meanwhile, the car does not appear to be burning any oil. And several years ago, I took a compression test and all was fine. I changed my PCV valve for the first time last week, but used an aftermarket brand. I have not noticed any improvement, and have seen from messages that an original is better. Do you think this could cure my problem? Why do the early Saturns have this 'drinking' problem?