I don't even get into all the oil debate these days. With the EPA having oil manufactures by the balls with limitations and requirments, can there really be that much difference? I mean, even Penzoil isn't bad these days. I go for cheap. If it's true or not, I won't swear to it but I've heard Walmart Super Tech brands are made by Valvoline. If I have over 10,000 miles on an engine and I know it's well broke in by now, I got straight to Super Tech Full Synthetic by the gallon. So I cheap out on the oil, but I go big on the oil filter. I run either a Mobil 1 or a K&N oil filter. With synthetic oil and a good filter, I don't even consider changing my oil until at least 10,000 miles. When I pull the dipstick and it's still Gold, pffft, I'm not changing it. I'll go another 4000-5000 before I change it. My engines are clean and they stay clean so I don't sweat it. My oil has been gold even at 15,000 miles. I then gave it to my bro for his oil burner to burn off since he's one of those that would buy it, a quart at a time at a convenience store and pay $4 a quart for conventional Best Value generic oil.
What most don't realize, engine oil DOES NOT wear out. It'll never ever wear out. So then you ask, if that's true, then why do we have to change oil? We don't change oil because it wears out. We change oil because it becomes contaminated and diluted. It can get diluted from condensation in the oil pan. It also gets diluted with gasoline/diesel from blow by. What turns oil black is suit from burnt combustion that gets past the rings. You keep a good filter that can trap the contaminants and condensation your oil will stay clean and function properly. Synthetic oil has slicker and better lubrication properties than conventional oil. Keep the engine slick, keep the wear in your engine down low as possible by using synthetic and keeping it clean, then you can get more miles out of engine. As the engine wears you might change it more often when it appears dirty but even worn, with a good filter and synthetic, I'd never change my oil until 10,000 miles.
Also keep in mind, we've all been told to change your oil every 3,000 miles. That's because that what the oil manufactures and car manufactures tell us. I guess if I manufactured oil I'd want you to buy oil unneccesarily too. Or have to bring your car to me for an oil change more often since my service department is what supports my stealership. Think about that. Go to the UK and see what they recommend for an oil change. Same car in a different part of the world. So why do they get suggested 8,000 miles for oil changes but here in the US it's 3000 miles. Doesn't make much sense does it?
