i currently run regular pump gas in my suburban.

i wanted to know, what would changing to the super premiuim do for me?
also, would i have to fully empty the tank first i.e., what risks are involved?

 

I found that in the hot, humid hawaii climate that 89 works best for me. Too high an octane will just increase the amount of carbon build up in your cylinders, increase hesitation and cost more money. In winter weather a lower octane is better. However, never go lower than the owners manual states.

 

Stick to low octane from a reputable company like Shell or Chevron. Your engine is designed around the burn characteristics of 87 octane at low altitudes, lower octane at higher ones. You won't see any gains by spending the extra 20 cents per gallon.

 

I don't think putting higher octane will make any difference but premium gas usually have additives to clean your engine and remove water from gas tank so that might help a bit. Of course you can buy additives at pepboys and do the same thing with regular gas.

 

Chevron and Shell put their cleaning additives in all grades, that's why I recommended them. I prefer Chevron myself. Running high octane on your 8:1 compression V8 won't do a damn thing man, unless you are getting knock. But putting a bottle of injector cleaner will help. I'd recommend getting two cans of Toyota injector cleaner from a dealer. It's really powerful stuff, and you want to add the cans to a full tank and then burn it all in a couple of days. It's great stuff, got an extra 1.5 mpg on my gf's POS 94 Mercury Topaz, and that pile had a 3 speed automatic.