So I know my 3.5 DOHC takes premium fuel only. Today at the gas station the idiot gas attendant decided to put a quarter tank in of 87 octane fuel instead of the 92. What will be the consequences of this and is their anything i should do?
ie. fill the rest of the tank with 92oct or get an octane booster

Don't even worry about it. The 3.5 is a "premium fuel recommended" engine. The knock sensor may pull back the advance on the timing, resulting in a slight loss of power, but it won't hurt anything.

John B.

wow, really? I thought it was a "premium required" engine, at least from what Ive heard and seen in the manual. I def did notice a loss in power.

Quick question...So is their any negative consequences if i decided to run regular fuel more long term other then the less power and knocking?

On the inside of your fuel door is a sticker that reads "Premium Fuel Recommended" - being in Oregon you wouldn't see that as regularly as those of us that get to pump our own gas. <img src="/forums/images/graemlins/lol.gif" alt="" />

I've found that my 95 gets roughly 1 mpg better mileage when running premium fuel, and it definitely makes more power - your results may vary. If I were you I'd track my fuel mileage through several tankfuls of regular gas and compare it to several tankfuls of premium from the same gas station, then its just a matter of personal preference - to me the improved acceleration is worth paying extra for, especially since it's slightly offset by the better fuel economy.

You shouldn't experience any knocking or pinging if your knock sensor is working properly - the ECU will retard the ignition timing if it hears any knocking, which is why the engine makes less power on the lower octane gas.