My '16 Mazda CX-9 turbocharged engine has a 7500 mile max oil change recommendation...with conventional oil in the turbo. I follow that, but I use synthetic due to the wider temperature range. It claims to have a monitor, but always comes to it's 7500 limit before the monitor says the conditions dictate the change.
My '17 Toyota Prius Prime plug-in hybrid has a totally stupid 10,000 mile or 1 year recommendation. Stupid, because the car can run about 30 miles full electric on the battery before the engine starts. There is no way to tell how many miles the engine has run. We're showing a total average mpg of 124 due to all the non-gasoline miles we have on the car.
The old '06 VW V-6 seized the engine at 50,000 even with oil changes every 5000, OEM oil filters, VW spec 5W-40 oil...never gonn'a be another VW product in this household.
The one year or other time based recommendation means little. Oil degrades extremely slowly when it just sits in an engine. It'll be fine for several years; I've seen the analyses. What does harm oil are short, cool runs or very hot runs. The algorithm based oil monitor systems take this into account very well.
Here's a listing of the U.S. oil Service Categories that shows the improvements over the years:
http://www.api.org/products-and-ser...d-classifications/oil-categories#tab_gasoline
Every few years the engine makers, oil makers, and chemical suppliers to the oil companies get together to create the next, better standard. The U.S. has two bodies that work together, A.P.I., the American Petroleum Institute, and ILSAC, the International Lubricants Standards Approval Committee, which is both U.S. and Japanese engine makers. The GF- rating we see is ILSAC, and the SN rating for gasoline engine oil & CK-4 rating for diesel engine oil are API (S for service, C for commercial). In Europe the ACEA, Association des Constructeurs Européens d' Automobiles, sets their own standards.
Modern engines are machined better. Fuels, both gasoline and diesel, are cleaner with lower sulfur content. Modern fuel injection systems burn the fuel more cleanly. Oils get better every few years. All these are the reasons oils are living longer. 10,000 miles between oil changes in Europe isn't uncommon, but they require higher quality oil than most Americans will pay for. I've run top quality oils here for 10k with good lab analysis reports.
I'll disagree with Bill about engines creating dirt. I've reviewed many lab analyses of used engine oil, and the dirt, the insolubles, is always low unless there is a specific problem in that engine. Oil gets bad when the package of essential additives becomes depleted, mainly the detergents and dispersants. And when the polymer viscosity index improvers shear resulting in lower viscosity. And when the oil molecules oxidize (one requirement of syn oil is a resistance to oxidation), or when the oil has external contamination from antifreeze, fuel, or dirt from a poor air filter (high silica reading). And high insolubles (carbon) from bad diesel injectors.
