So far I've been using Pennzoil 5W 30 and had no problems. Over the past 2 weeks (yes, 2 weeks!) I've been putting in a remote starter and putting my engine through **** trying to get it to work. I bet it's seen more starts over these few days than it will the rest of the year! I'm going to give it some fresh oil in the next couple weeks (been 3 months, but only 1,000 miles). I was thinking about going with Pennzoil High Mileage. Does the HM formula have moly in it like the Purbase? Any advantages to using it? The engine is a 2.4L Twin Cam (Grand AM) it sees frequent 4,500RPM shifts due to my heavy foot. It has just under 83,000 miles (75K of which were highway/freeway). Synthetics don't really interest me as I only drive the car about 3K-4K a year and I do 3-4 oil changes regardless of milage.