I had a friend of mine recommend a
oil manufactured by Lubrication Engineers it is a 15w-40
synthetic oil that is a parifin based product so it does not breakdown as easy. From what I understand the military uses it in their vehicles because of its long last capabilities. Not sure when the next time it will get changed is their thinking. At 3.75 per quart it aint cheap & can't exactly go down to autozone and pick up a case when you run low.