I have a question as to how long oil can keep inside a motor that is not driven for an extended period of time. Before finding this site I was a stout 3/3 guy for all my vehicles. Recently I have decided to start using the OLM's equiped in my truck and my wife's GP which tend to go at least 4-6k miles before recomending a change. However, for my GTO I do not drive it in the winter so it only sees the road 6 months out of the year. In the past I have always just gone by mileage (3k intervals) regardless but have always wondered if I should dump the oil that sits in the motor over the winter months even if it only has 1 to 2 thousand miles on the oil. I was thinking of bumping my OCI up to 5K miles but worry about the condition of the oil after the winter from not driving it. The oil is synthetic so I don't know if that alows it to keep better than a dino would or not. Also, right now I put about 6k miles a year on it but expect that to increase next year to about 8-10k as my work office is moving and will be a farther commute and at this time I am not confortable running the same oil for that long of a span to just dump it once a year at the begining of spring.