I spoke with Valvoline yesterday and they claim that the difference in the oil as I stated above is a better crude grade only and that now the Valvoline is THREE TIMES BETTER! No changes according to them on any mineral content including Zinc and Phosphorous or ash..... I'll be sticking with them... I guess.

Edward R. Cozzi
What kind of Royal Purple oil do you mean, motor oil or racing motor oil.

I like amsoil 20-50 sever synthetic racing oil.

The major difference is the racing oil has anti-foam additives.
It's much more expensive and I only use it in actual race car motors. I've never had a problem using Royal Purple in ANY application I've used it.

There are many myths out there about synthetic oil and its use. I've heard so many "experts" pontificate about the horrors of changing to a synthetic oil and most of it is BS.

If my wife had a vibrator that used oil, I'd put Royal Purple in that thing too.

I use Walmart Brand SAE10. You can pick it up for $.89 a quart and the thinner oil allows my engine to rev higher which allows me to run a bigger prop. I picked up 10 mph!

I bought some Valvoline a few weeks ago, to change the oil in Debbie's truck. I thought it was the clearest oil I'd ever seen. I've used Valvoline before (it was my dad's favorite), but I never remembered it being that clear. I guess they did change the formula.

Probably the best argument for synthetic oil right there. It takes horsepower to turn that oil pump when you're running 40 or 50 weight oil. Unless your engine builder put massive clearances in your engine, you shouldn't NEED oil that thick.

I am running Mobil 1 Synthetic 15w-50 in my 540's. I change it every 20-25 hours. Easy to do, good insurance. I also have the large HP6 filters. Kind of pricey, I have 12qt. pans and huge coolers but I think it keeps the motors really fresh and running well. They are in the mistress. The Oil always looks great.

Try looking at Alysin oils.