Darn. I've been clueless. I thought all gas was the same. I guess I was wrong. Need to siphon the tankful of Speedway out of my Porsche!
Spoke with my SA and he related that the Porsche head mechanic does not recommend any fuel additives for the Porsche and one other recommendation the mechanic made was buy brand name gas, Mobile, Chevron, etc because some Gas stations are selling lower quality gas and the attraction for some is the lower price.........I guess it's just another example of you get what you pay for.