I have a 70 Camaro that only gets driven around 1000 miles per year. There are NEVER any short trips. If I start it, I drive for 20 miles or more so the engine never gets shutdown until it has been at full operating temp for awhile. After a year, the oil (Valvoline Max Life 10w-30) looks as good as new. Seems like a waste to change it but I dont want to harm the engine. Any opinions if it is safe to keep the same oil for a year or more?