Most cars run fine on regular. Most newer cars will recognize premium and deliver modestly better performance. Most additives won’t deliver near what they promise.

You want to talk snake oil, I wonder why you’re singling out STP. At least they’ve got active incredients that really do work to clean your engine. Take Lucas for instance… is LITERALLY mineral oil. Its got NO ACTIVE stuff in it.

What a racket.

And although I’ve heard of additives for fuel line freezing, fewer and fewer people seem to be doing that, maybe its the move to fuel injection, maybe its the additives in gas, I don’t know, but it seems unnecessary.

Find a friend with a borescope you can put in through a spark plug hole, or take it to a service shop and ask them to inspect it for excessive carbon in the head. This can be caused by prolonged operation at low throttle (how often do you run at wide-open throttle for 5+ seconds at a time, like get on the entrance ramp and just womp on it?), dirty injectors, or restricted intake (changed your air filter lately?).

Anyway, water remover doesn’t work by segregating the water from the fuel — that happens normally. Oil and water don’t mix, right? So water vapor that gets into the tank condenses and collects in a “puddle” on the bottom of the tank, since it’s heavier than gasoline. Occasionally the fuel pump sucks up part of this puddle, and a moment’s worth of water gets delivered to the injectors instead of fuel. This causes periods of rough running, power loss, even stalling if there’s enough of it.

Water remover is just alcohol, which is combustible like fuel but also dissolves water. It mixes with the puddle in the tank, so next time the fuel pump sucks some up, the engine doesn’t notice (much). Running a few gallons of E10 instead of your regular fuel has the same effect as adding a bottle of additive, but costs less and has no additional packaging to throw away. In spring and fall when condensation is most likely, I stop at the local Sunoco every few fillups, because all their blends contain 10% Ethanol.

At most stations, even the cheap grades contain the same detergents and additives as the higher grades. But the specific types of additives vary between brands. Every detergent has a set of things it will dissolve, and a set of things it won’t. It’s like moisturizing hand soap won’t clean moisturizer off your hands. Running different brands of gas (with different additives) allows them to clean up the mess left behind by each other, and has the same effect as a bottle of additive but without the cost or the bottle.

As for high-compression engines, it’s not just Vipers and Vettes! I was shocked and somewhat pissed off when, a week after having bought my Toyota, I stopped to fuel it up and found the “premium fuel only” sticker inside the fuel door. The dealer never told me that the tradeoff for having the upgraded “2ZZ sport” engine was that I’d be paying for high-octane gas for the life of the car! Bastard. Anyway, a lot of the smaller cars achieve the performance they do because of high-output, high-compression engines, which require high-octane gas. If this is the case, it’ll be in the owner’s manual or labeled inside the fuel door.

Also, I hate to be the 10000000000th person on the internet to point this out, but real-world, “seat-of-your-pants” experimentation is hardly useful when there are so many variables to address.

Gasoline composition can vary from season to season, and you didn’t even address that effect in your experiment. Did you control for things like ambient temperature, humidity, wind, altitude, road surface and tire pressure variations? There are hundreds of things that can significantly contribute to variations in fuel efficiency.

There’s also the human factor to consider. Was this a double-blind experiment? If not, what steps did you take to minimize the psychological factors of the experiment?

I would hesitate to call BS on conclusions drawn from the results of countless controlled, scientific experiments when all you’ve got to go on is non-scientific observation.

This a great writeup. I can’t count how many middle class suburbanites I’ve had to educate on the uselessness of using higher octane than their car requires. What’s especially curious is that they always sound surprised…sheep…

As for lead, the only reason I know of for lead in gasoline is for valve seat lubricant. Maybe it did something else, but running unleaded in non stellite valve seat heads would lead to impacted valve seats. Alloy valve seats is afaik the main difference between vehicles that can run on unleaded, and those that need lead.

It is my opinion that we are getting scammed with this “oxygenated” fuel ethanol today. Mileage really takes a dive when this stuff is in the gas. And yes, I have had fuel lines freeze on me, and drygas can prevent that from happening. I’ve also seen people that swear by Marvel Mystery oil in their gas. I’m not one of them though.

I am a big believer in oil additives though. I have seen Tufoil do amazing things.

you suck it into your engine through the break booster line and let it sit for 10 minutes then start it up and watch the smoke show as your exhaust spits out lot of carbon build up

Check out some videos
http://video.google.com/videosearch?q=seafoam

The second thing I’d like to point out is that the fuel/air mixture in a cylinder is not supposed to explode, as you stated, when operating normally. Gas is designed to burn - very fast, creating the energy necessary to move the piston back down. When the fuel/air mix explodes (as you said, called ping or knock) it is a bad situation that will cause damage if not corrected by the computer or higher octane gas.

http://en.wikipedia.org/wiki/Octane_rating

I remember in my sophomore organic chem class having this explained to me and having a real “ah-ha” moment. Thanks for putting this up, it’s great to see the championing of critical thinking and rationality for a market that pretty saturated with hyperbole.