OK, maybe I should restate my question. First, cost is not an issue, but I do look for the best bang for the dollar. My point is that Royal Purple will cost me $11 per quart vs. Mobile1 at around $4, obviously that is almost 3 times as much. Is the Royal Purple really that much better? I would rather spend the same amount and change the oil 2 more extra times between normal oil interval changes!

Also I will tell you that the engine builder recommended against Mobile1 suggesting I stay with a racing synthetic. I am not sure what the difference is between a racing synthetic and Mobile1 synthetic?

The engine is running gas (C114) so nothing real fancy or exotic. Normal engine tempretures, filled block with radiator cooling the the heads. Presently the Royal Purple used is Racing 41 (10-40W).

Thanks again,
Mike