A while back a customer was concerned because she had always used Mobil 1 in her car and we did not put in Mobil 1. In fairness to us, she had not asked for Mobil 1, I think because she simply forgot. I was able to reassure her that the oil we put in her car was far superior to what was specified in her 2002 Nissan when it was manufactured. With certain exceptions, which I will get to down the page, what you are looking for in motor oil is not that complicated. You should not second-guess the vehicle manufacturer’s viscosity recommendations. These may or may not vary according to the anticipated temperatures at which the vehicle is going to be operated. A straight weight oil changes absolute viscosity greatly with temperature — example simple 30 weight will be much thicker at 0* F. than at 200* F. Not good, thick and slow to flow when the car is started in cold weather, thin at operating high operating temperatures. 10w30 motor oil means at a lower temperature — typically but not always 0* F., the motor oil has only thickened as much as a straight 30 weight, at 200* F. it has only thinned as much as a straight 30 weight oil. This is done with additives and/or synthetic base stocks. Since my customer’s Nissan was built in 2002, oil standards have become much more stringent. Besides the American Petroleum Institute we have ILSAC whose recommended oil quality classifications have become much more stringent. Look for these on a bottle of oil and it will meet the latest most stringent specs (except keep reading and see below!) GM is an exception and formulated its own standard “Dexos.”
To meet these newer highest standards, API “SN”, ILSAC “GF-5” or General Motors “Dexos,” the oil will be a synthetic blend if not a full synthetic. For today’s passenger cars the most common oil is 5w-20 or 0-w20 viscosity. To my knowledge these are sold as full synthetic only.
Diesels and certain extreme high performance engines, often European, sometimes have their own proprietary standards but essentially if the oil is API “SN” and ILSAC “GF-5” licensed and of the manufacturer’s recommend viscosity it is the best available at this time and that is what is used at Don’s Automotive for your Asian model car or your non-GM domestic model. ILSAC is working on a yet more stringent “GF-6” standard and the American Petroleum Institute will sure be replacing “Service-SN.” When oils meetings these standards are available that is what Don’s Automotive will keep. We keep diesel spec oil and we keep Dexos for GM products.
Mobil 1 and Castrol brands are examples of powerful name brand recognition marketing that got a jump on the competition but that does not mean other oils are not every bit as good.
Modern cars can go a long time between oil changes, but PLEASE don’t forget to pull the dipstick occasionally between changes!