Pennzoil and quakerstate are the same oil read the back of the bottle, Castrol edge used with a Fram Tough Guard filter is recommended for 15,000, RP for 12,000 with their filter, Mobil 1 12,000 with their filter. Thats if your using full synthetic. Do not use Rp in older model vehicles that have some oil leaks already because the leak will only get worse. Rp is meant to clean and condition, not be lumpy and fill in the leak.