Seeing Michael Waltrip’s sad-sack face on the front page of CNN and reading the associated story from a couple of angles got me to thinking about how little most people know about fuel additives — and how much BS I’ve heard about ’em. I suppose what really set me off was how excitable everyone was that the additive discovered in Waltrip’s intake manifold was “rumored” to be a component of jet fuel.
Even if this turns out to be true, this is sensationalism at its finest. While the words “jet fuel” might conjure up images of sleek fighters ripping through the sky or demonstration-only dragsters screaming like bats-outta-hell down the 1/4 mile, the truth is that jet fuel itself isn’t very exciting. It’s darn similar to diesel fuel, though they differ dramatically in additives.
But what about all the over-the-counter fuel additives available to you? In a classic case of life imitating art — the art of BS in this case — check out this description of STP’s Gas Treatment:
“STP Gas Treatment improves quality of gas by adding powerful cleaning agents to help fight accumulation of harmful carbond, gum and varnish deposits in the fuel system that can reduce performance. Also engineered to remove water, which can lead to fuel line freeze. Thsi product is made with Jet Fuel, a high quality carrier of active ingredients. This product is safe for all gasoline engines.”
Let’s tear that apart and see what it really means — past the jump.
Note first that STP uses the phrase “Jet Fuel” — the capitalization, apparently, indicating that this is a proper name for a product of some sort — as opposed to plain ‘ole “jet fuel,” which is the fuel used to power jets. The sentence then goes on to describe “Jet Fuel” as “a high quality carrier of active ingredients,” which (again very subtly) indicates that “Jet Fuel” is an inactive ingredient. Or more precisely, it’s unimportant filler that carries the tiny amount of real stuff around. Think of Jet Fuel as the inert powdery crap in pills that helps to distribute the few milligrams of actual medication.
So did Waltrip put STP in his fuel? It’s doubtful. My guess is that the ‘trip wanted was additional octane. As far as I can tell, there are really three purposes for fuel additives:
1) Cleaning Your Fuel System
This is a laudable goal. Over time, some of the varnishes and other nastiness in gasoline will indeed separate out and deposit themselves in your fuel system, and running a decent cleaner through your engine every so often will help to keep those deposits from growing. Cleaning is also generally responsible for the “saves gas” print on additive packaging as it’s true that a cleaner fuel system will help efficiency.
But what many additive marketers fail to tell you is that this is a relative thing. If you’re fuel system is already quite clean, you’ll see no improvements in power or mileage by running cleaner through the system. Even if your system is slightly dirty, you’re not going to see life-chaning mileage bumps.
In fact, the most profound experience I’ve had to date with cleaners came from running some injector cleaner through my 1993 Miata, which hadn’t seen any since I’ve owned it (and probably not before). After I burned a full tank with the cleaner, the car did seem to run a little smoother, and I thought I might’ve sensed a little increase in performance. Maybe.
2) Boosting Octane
Look, I’m no fuel engineer, but after spending a lot of time under the hood, I can tell you this: Octane is most simply described as a measure of fuel’s anti-knock properties. “Knocking” is caused by fuel succumbing to the very high temperatures and pressures within the combustion chamber and igniting before the spark is delivered. This is a bad thing as the mis-timed explosion causes the cylinder to push against the engine’s normal operation. It causes extreme stress to the engine in a variety of methods. Higher octane fuels can withstand higher temperatures and pressures without pre-igniting.
While cleaners generally claim to “save you gas,” octane boosters claim to deliver “increased power.”
To some extent this is true. As you increase the compression of an engine, you’ll need higher and higher octane fuel to prevent pre-ignition. Since many modern engines feature computer-controlled timing complete with a “knock sensor,” they can retard the timing when they sense knocking to prevent damage. Retarded timing, of course, means less power.
So theoretically, if you were running your computerized vehicle on fuel with too low an octane rating for its compression, and you then upgraded to higher octane fuel, you’d likely see a performance gain from the correctly-adjusted timing. But the vast majority of engines today are designed to run correctly on 88 octane fuel — the lowest normally available.
The bottom line: If your car is designed to run on 86 or 88 octane fuel and you fill ‘er up with 93, it’s not going to make a damn bit of difference — except to your wallet. The same goes with aftermarket “octane boosters.”
As you might guess, if Waltrip could increase the octane of his fuel beyond that of his competitors, his crew could then adjust the engine to take advantage of this to make additional power
3) Preventing the Absorption of Water
I’ll admit that, having lived in Texas most of my life, I don’t really know much about these additives. I understand, though, that gasoline can absorb water whle jet fuel doesn’t, so freezing water is far more of a risk in jet aircraft than in gasoline-powered cars. On the other hand, in the wintertime up north, it can get cold enough to cause problems, so I’ve heard of people using additives to protect their vehicles.
It’s my firm opinion that unless you’ve made modifications to your engine that require additional octane, and unless your fuel system is seriously dirty, you’re not going to see any benefit at all from additives like the one pictured at the top of this post. You may feel better about yourself or even get a warm-fuzzy inside because you’re taking care of your car, but that’s the limit of the benefit. Your car can do without.
Of course, if you have a different opinion, I’d love to hear it in comments.
STP Gas Treatment [STP]