[puddleglum]

Kia Canada demands that oil be changed every 4 months or 5000miles whichever comes first to maintain warranty. Considering how little I drive my car, I've pushed it to six months, but I may look into oil sampling. It's probably no cheaper than changing oil, but I'd have the benefit of knowing if there were signs of wear in the engine and have some data to back up a longer service interval. I've only put on 3000 miles in the last 11 months so 4 month changes are overkill.