I usually use Mobil 1 5w-30 motor oil, but I need to get an oil change this week and I don't see any of my local retailers with any specials on the oil.. (It's $7 per quart out here, then about another $8 for the oil filter.. ouch!) But, I did find a coupon for Pep Boys where they have 5 Quarts of Royal Purple oil and a Royal Purple oil filter for $45. Is Royal Purple okay for regular cars? Is it okay to go back to Mobil 1 for the next oil change? I've only seen Royal Purple used in my family's race cars.. I don't know how well it works for regular cars..