Originally Posted by axmea?

I don't know if there are regulatory influences on intervals as it is merely mfr recommended intervals. Part of it is cultural and part of it is marketing by those little oil change shops. The 3000 mile/90 day rule has been imbedded here in the US for a long time and hard to change. Oil change shops will want shorter intervals to get you back in their bay. I think the average consumer needs to educate themselves on oil change intervals basing it on short distance driving/frequency, mileage of vehicle, what the vehicle is used for, vehicle mileage, driving conditions, etc. Many still think that today's motors and oils are the same as those from years ago.