Quote Originally Posted by Bill Howatt View Post
The biggest problem with deposits and fouled plugs was from the lead in the gas and carburetors being poor at ideal fuel mixtures especially for rare highway driving. Back in my youth, drag-racing friends used to buy high premium gas across the border in the US because a certain station on the way to the strip had higher octane gas. Idea was to be able to fudge the timing a bit more without pre-detonation and presumably get more power.
Nowadays, I hear some people talking about better gas mileage and maybe power if they use premium gas. Personally, I take the more power part with a grain of salt and a typical care has more power than it needs no matter what it's running on. A Google search says premium is generally 20-25% more expensive than regular and I doubt anybody is getting that big of a mileage increase to justify the cost.
IMO, just look in the little book they gave you, you know, the one you used to setup the radio presets, and find the headlight switch, and see what the manufacturer tells you to use.
While premium is recommended in my torch red mid life crisis two seater it does just fine on an 87 octane 10% ethanol blend. What I find most impressive is that if I drive it without having to feel those 460 HP it will average 30 MPG. It's hard to go for a cruise and not at least tickle the throttle though a few times. I tried premium and saw no improvement either in mileage or performance. It might be something you would have to go to a track to see though.