There is a vaild argument against changing your oil too frequently. After you change your oil and then start up the engine for the 1st time after the change, there are a few seconds where the engine is starved for oil as the oil filter fills and the system pressurizes. More engine wear occurs during those few seconds than in 10K miles of driving. So the more you change your oil & filter, the more engine wear you'll get. I fill up my new oil filter with as much oil as I can get into it before putting it on, but the engine still starves for oil for a couple seconds. The determining factor in engine oil life is when it contains so much contaminants that they precipitate out forming sludge. This is an advantage full synthetic oils like Mobil 1 have. They contain less viscosity enhancers meaning there are more lubricating molecules so full syns can suspend more contamanents and last longer. If your driving is mostly long trips, you oil may last 10K miles. But if you do mostly short trips ( a few miles ) starting & stopping the engine a lot 5K miles could be too long.
