seems like the past 6,000 miles of using PENNZOIL Platinum synthetic oil in a 5w-30 for 2000 PRIZM , it's been burning more oil and may have very slight leak from valve cover . Like how much quiter it runs , but otherwise most likely going back to the conventional oil . Thing is , should I use the 4 qts. of the PENNZOIL syn-blend ( 5w-30 ) I have for next change and then go to the regular PENNZOIL ( or CASTROL GTX ) for good ? Or be o.k. to go right to the dino , since only a short period of using the synthetic ? Figure after that just use the regular oils on sale , such as CASTROL GTX , PENNZOIL ( Yellow Bottle ) , etc.. If consuption and leak continues after switch back to dino , may give the VALVOLINE Maxlife a shot . THANKS