Back in the late 50', my first girl friend's father had a 1950 Buick with a straight 8 engine with 150,000 mile on it. He changed the oil once at 100,000 miles. However, he changed the huge oil filter every 3000 miles and topped of the oil. They don't build them quite the same these days.

Over the years I have seen many niche oil companies come an go, all claiming incredible results. After a few years, they are gone. Last weekend I visited a Toyota dealer selling Royal Purple synthetic - never heard of this brand before walking into the dealer's part room.

I recommend a major brand of Synthetic oil like Mobil One or Castrol Syntech. The few extra $$ is well worth it and you will be rewarded with a long engine life.