I don't feel comfortable letting oil set in a car for more then a year. The additives have a shelf life even if the oil itself will sustain that long. I would say annually just like a couple of other poeple.

But then again, a friend told me a while ago that the Nissan dealership he worked for got a car in from a lady with an issue. They found the issue fairly quickly when, just on a hunch, he asked the lady when the last time she changed the oil. He said that she looked at him a little funny and asked why was that needed. She bought the nissan brand new and somehow managed over 100k miles, i forget the number he gave me....... He said the engine did not look pretty, but there is no telling if the maintenance was done or not, so she could have done it without knowing what she was doing.

So I may definitely be wrong, but by no means would I ever suggest doing the same thing!!!!!!!!!!!!!!!!!!