Here the answer is that as the Stpaulguy. Most NASCAR car have a compression ratio of 11-12.5/1, so if the unleaded gasoline is in the higher compression ratio engine then the fuel will eventually fire off before even having the spark plug to spark the fuel. This would cost fuel and performance. If the premium leaded gasoline get into the engine that have a compression ration of 10/1 it would be a lot harder to spark the fuel, it sometime may not evening spark the fuel. 87 is the choice for most engine because everyone want a cheaper gas right, but I recommend that it your towing or anything heavy duty to your truck, it prefer the 91 but not 94 premium.

...all gas is unleaded.

Difference between the two grades is the Octane value. And really the only cars that are gonna require Premium are top end performance cars. Really all it is, is when the fuel explodes to curb engine knocking.

As to what would happen, likely nothing if the vehicle runs fine at the lower octane fuel. You won't notice any difference in performance, either.

Most premium gasoline are non ethanol such as she'll v-power or petros superclean (91 not 94 as ethanol is used to bump it to 94). Stay away from no Name stations as they are almost always 10%+ ethanol content. Ethanol eats away at plastic seals and over time can harm your engine.if you have a "flex fuel" vehicle they are made to better withstand the harmful effects of ethanol but still not recommended. You will not notice much difference running 91, a little bit more peppy and better mileage on the highway. If you want you can also get your ecu reprogrammed and that will add a fair bit more power and they can set your octane to 91.

Your truck's engine was designed to run on regular grade (85-87 octane) unleaded gasoline. Paying more for anything else is an absolute waste of money.

If your truck was designed for 87, adding premium will only make the gas companies richer. You need to understand that octane has NOTHING to do with power. Higher octane gas burns slower to prevent pr-ignition in high compression engines. Use it in a low compression engine and it's not only a total waste of money, but makes it harder to start in cold weather.

I own a '02 Dodge Ram 2WD king cab. I was curious as to what type of gas I could put in. I've always put unleaded since it's always been my main choice. I don't have the truck manual. So I was wondering what would happen I switched up gas. Would it hurt my engine if I did? No where does it say "Unleaded Only". Gas is rising and premium seems a better option to low grade.

Please and thank you.