I have an '02 altima with a history of cold start problems. This last week it did it again and they towed it to a shell station in manassas, va to guy who said the pcv hose was off and that it needed an induction and oil change because fuel was coming out the tailpipe and he needed to flush it out to prevent carbon build-up, and that the oil had fuel in it.
Here's the problem. Nobody I know can see how fuel got in the oil because of a loose pcv. Nobody thinks a loose/disconnected pcv hose will keep a car from starting (maybe run rough, which it didn't). Nobody knows why a 4 year old altima that has never sputtered or knocked could have enough gunk in it to need an induction. Besides which, I just had my 75K service with oil change only 6 days earlier, and those guys always notice extraneous gunk.
This is what I think. Every year on the first workday after Christmas break, the car won't start. The engine turns, battery is good, but it won't start. I think it's the variable valve timing. The car sits undriven for days in icy weather over xmas break, the oil gets all viscous, and I get to spend the morning at a shop watching guys bill nissan warranty for new starters, batteries, and random doohickeys when all I need to do is switch to synthetic oil. It warms up in the shop and starts, the mechanics declare victory, and it runs fine until next Christmas.