What type of oil do you use?

[CastIron]

I have been using Pennzoil on all my vehicles for 20+ years. None of my engines have had oil related issues. I use conventional 10W-30 in my 69 C15 with a 350 crate motor. I run synthetic 10W-30 in my Chevelle, and both my more modern cars use synthetic 5W-30. I almost always get 5 quart jugs on sale for $20. I also use NAPA gold filters on my V8s, AC Delco & Purolator filters on my newer cars. I used Fram for many years with no problems as well. I would say that the important thing is to change it and make sure you don't run low on oil. I change oil and filter generally every 3k miles or 6 months, depending on what comes first.