Regular or Premium, the final answer?

[coastalcruiser]

So what's the outcome? Is running on Regular OK? Will it kill my engine? Will I violate my warranty?

[chadk]

Yes
No
No

[Mtbcoach]

chadk previously said:

Yes
No
No

X2, though you won't get a "final answer". If you "want" to spend money on higher grade, its your money. But, it really isn't necessary IMHO...

[Gottagetone]

I made the switch about four tanks ago and I can see no change in performance. I ran Super for a year(32k miles) and decided to give it a try. What I did find was about $5 in my pocket rather than in my tank.

[Dissident]

I dunno, I figure the manufacturer doesn't say to use it because requiring premium sells more cars...

The Straight Dope: What's the difference between premium and regular gas?

I noticed about a 2-3 mpg drop in gas mileage when I've tried it in my car, which pretty much canceled out any savings. I doubt the power loss is anything your butt dyno will notice, but it's there too. Whether it's necessary is determined by the compression ratio of your motor, and even a knock sensor means knock has to happen before the computer adjusts...

It's like anything else; you can probably exceed the trailer weight by a bit, drive on your tires past the wear bars, or whatever. If it's worth the risk on a $30K vehicle to (maybe) save a few bills, then go for it, but really, you bought the wrong vehicle if you wanted to be thrifty :P

Other than running an engine without oil, there is probably nothing that you can do that is more detrimental to an engine than detonating it. In an ideal combustion cycle there is a controlled burning of the compressed fuel and air, but during detonation there is an exploding of the mixture with a instantaneous release of all its energy, regardless of where the piston is in its stroke. The timing of the auto-ignition will have a direct effect on where the damage takes place.

Detonation very early in the compression stroke is usually the silent killer that goes unheard by the driver. This form of combustion usually results in rotating assembly failure by attacking the connecting rods and bearings. Detonation that comes nearer to TDC or slightly after is usually heard as pinging and will likely result in the burning of the piston or the lifting of the ring land from the piston. The force from the colliding of the multiple flame fronts can be likened to the wake of two boats travelling in opposite directions on a lake. When the two wakes meet, they usually peak and absorb the energy of each other. The more dominant wake will still have some leftover energy and will proceed weakly in its original direction. The same holds true for colliding flame fronts in a cylinder. If you have one flame initiated at the spark plug and another started independently of the plug, usually the spark-initiated front is the dominant one. As the two flame fronts collide, the pressure in the cylinder rises from the compacting of the molecules. Historically, the normal flame front has enough energy to run over the abnormal one but uses a lot of its energy to do this. Add to this that the abnormal combustion has consumed a portion of the combustible mixture that filled the cylinder, and the least result is a loss of power, if not a damaged engine.

[DEWFPO]

I give up.

DEWFPO

[toyotaoffroadFJ]

didnt toyota release a letter to say use of 87 octane is fine...ive been using 87 since new..no issues with pings or anything like that.,..

[knight_hunter3]

87 octane is fine...the cmputer adjusts itself for thel ower octane.....running the cheaper stuff will give you a slight drop in mileage (ive seen it got from 17 to 16 in town and 23 to 21 on the highway) but you wont notice much else. I only use the good stuff when I tow my snowmobile or 4 wheelers.

The computer adjusts.....thats what its made to do....and Toyota said it woudlnt hurt.....so why pay for the extra octane if your just doing daily driving.....save the expensive stuff for when your towing or need the hp and torque.

[DoWork]

regular

[EschObfus]

The short and skinny is that Toyota has said it is ok to use 87 octane. The reasoning behind the initial requirement was that the hp/torque numbers published for the 1GR-FE engine in the FJ were done using premium fuel; or some such...