I was just wondering if I can use diesel gas in my 2x4 Chevy Blazer, I have only used unleaded, I just got this vehicle about three days ago. Or could I use premium gas? But would I get better gas mileage? And by how much? Any help is appreciated!
Absolutely you can not use diesel fuel in a gasoline engine. That's like running an ostrich on cat food. Gas engines do not compress the fuel enough to fire diesel fuel. The engine will not start or run on it.
Higher-octane gasoline does not give you more power. It allows engine designers to design engines to produce more power. The higher octane is needed to eliminate the drawbacks of those designs. Your engine is not designed to need high octane fuel and there is no advantage to using it. It is harder to fire because it is formulated to resist premature self-ignition, (spark knock and pinging), and that makes it more likely to cause a misfire and reduced fuel mileage when you have marginal spark plugs and wires that have been ignored too long.