Shell or BP Gas

[laxman0324]

I use wawa...

 

I used to since it was 5 cents cheaper per gallon but then while Im waiting I have to get at least a lemonade tea, usually a hoagie with it which negates that savings.

[IncidentalOffroader]

Fueler: I agree with most of what you say, I do however believe that most manufacturers use a better package of additives in their higher octane fuel, and every couple tanks I fill up with premium. The only difference I notice is my truck idles a lot smoother since its on 105k and I think still on the first set of plugs. And for some reason I get about a half gallon better with premium then regular, but I think the Shell I use has some of the methane? in it, not sure if thats the right chemical or not.

 

I remember there was a Consumer Reports article that listed the brands of gas that varied their additives with octane. It came out back in the late 90's, so the info might be out of date by now. But I wish I could find a similar list for today.

 

As for using premium, I think we all agree that "high octane does nothing for you if your engine isn't prone to knock." Some engines are prone to knock by design (ex. high-compression ratio). But engines can develop knock problems with age or malfunction. With age, carbon and soot deposits can build up in the combustion chambers, which retains heat, elevating the temperature, and inviting pre-ignition. One could also argue the deposits increase your compression ratio. As far as malfunctions go, one example is bad timing (obviously), another is the EGR valve, which is supposed to route some exhaust gas back to the intake air specifically for the purposes of reducing pre-ignition.

 

Having said all that, if you are happy with results with premium, there's no reason for you to stop using it because it doesn't fit our expectations based on what we "know".