Lots of pros and cons to oil and types of oil. if you look on the back of a quarter oil, there’s all these numbers and letters that represent all types of different things. I nowadays it doesn’t matter what the crude is or where it came from more importantly, it’s what the chemists do in the lab do to the oil adding different types of new synthetically engineered lubricants. I’ve always looked at it this way. Every 3000 miles is the best interval. Basically winter spring summer fall. now because of the increase in save the Earth green piece type, they put pressure on the manufacture to up the interval because they want to know where all this used oil is going professionally most of it is being recycled, so they went to the chemist to improve oil that’s how synthetic was born synthetic oil has its pros and cons. Yes it’s a good lubricant higher flashpoint doesn’t readily mix with water but if you have that problem it’s not oil related however, the FAA does not allow synthetic oil and piston operated airplanes. The oil synthetic that is has another feature dirt doesn’t stick to it , a lot of people change the oil synthetic and say it’s still clean so where does the dirt go it stays in the engine I have experimented using paraffin oil for 500 miles after and it comes out dirty most important thing is that you change oil and should never exceed the manufactures recommendation I could go more in depth, but I won’t …… happy motoring!