Up until last year I was doing every 5k, now I'm going out on a limb and doing 6k. I use regular dino 5W30. I'm still leary cheap to shell out for synthetic, especially when there are (mis)conceptions about
a) switching to synthetic on a higher mileage car, and the synthetic cleaning out gunk that help the seals, well, seal.
b) compatibility between synthetic brands if not sticking to a single brand
c) Synthetic brands not really being true synthetic.
d) The shorter intervals give me a chance/excuse to examine the underside of the car for potential problems. (yes I do my own oil changes) - example just last week I noticed some of the clips holding a plastic shroud under the engine compartment had fallen off.
e) I left a 1/2 filled jug of 5w30 dino outside overnight when it was -30deg. It was not thick as molasses when I tilted the jug in the morning.
I really hate the term "cheap insurance". What will it insure against, and exactly who will pay out?
Edit: I'm of the opinion that synthetic oil is just like premium gas... if the car isn't designed to use it, then there is no advantage. Then again there may be no advantage to 6k intervals, instead of 8k or 10k.
Flame suit on...