Hey, I'm no chemist so I won't try to explain why fuel works the way it does, just wanted to take some time to explain the effects of the properties of modern "Designer Motor Fuel". No, I didn't coin the phrase, but I like it enough to use, if you've read any of my writings on fuel before you know I've used it before.

Re-Formulated fuel is what you've heard it called most often, you've probably had some pretty rank four letter names for it, I sure have. You know how well milk goes down when it's sat around too long, well think of todays designer motor fuel the same way, for your engine. Old milk, skunky beer, old Designer Motor Fuel. Nasty, just nasty.

First off, just a little explaination how your engine uses fuel, for those not aware. An engine does not burn liquid fuel, it burns the vapors evaporating from the fuel. That is why an engine has a choke or primer to make starting easier when it is cold. The more fuel in the system, the more fuel is vaporized to be burned. A hot engine will vaporize fuel quickly and doesn't need the extra shot from a primer or choke. The hotter the engine, the less fuel it needs. Even then, a lot of liquid fuel doesn't burn before leaving the combustion chamber. Most of that will burn somewhere in the exhaust system but that fuel is being wasted. Enter, Designer Motor Fuel.

This funny stuff is designed to vaporize much faster, it has all kinds of chemicals and properties in it that we never had in fuel 30 years ago, and none of it makes for more power, if anything it makes less. What it does is allow the liquid to vaporize faster, thus, smaller quantities of liquid fuel entering the combustion chamber are needed. This provides better fuel economy and lower emissions. That part of the deal is OK. But there's a down side and the down side can be a major problem for L&G equipment that may set around for months not being used. It's a problem for equipment owners who only use their equipment a short time each week, and don't use up that re-fill can of fuel fast enough.

It's a great profit making problem for the repair shops, but can also be a nightmare trying to explain to people why they have a problem. They want to think the shop is ripping them off. Well, we don't have too as long as folks don't get it through their head that todays Designer Motor Fuel ain't gas anymore. Hmm, where have I heard that before? OH yeah, that's another of my BS Tips. So this is really just a repeat of an earlier tip. Just trying to re-explain it so more people will understand.

The properties of todays fuel cause the fuel to go bad in a short period of time, much like that milk or skunky beer setting in the refer. It changes, metamorphoses into something your engine don't like. Around thirty days old it starts to become difficult to start a cold engine. After a couple of months it starts to leave deposits on valves as it isn't burning very well. You risk having the valve stems glued to the guides. Stuck valve. I've seen cams broken from trying to lift a stuck valve in flatheads, bent push rods and broken rockers in OHV's. This is user damage and is not covered by the engine warranty. You can imagine how upset some folks become when they find they have a major engine repair bill when their engine only has a few hours on it and only 3 months old, still well inside the warranty period. But the engine manufacturer didn't make you use old fuel.

Depending on certain factors, after 2 to 3 months, old fuel will start to gum up carbs just setting around. The fuel line will soften, actually melt down. Again, these are not warranty covered problems but the repair shop takes the heat from the consumer. We are the ones the consumer sees and talks to, not the fuel companies, not the engine manufacturer. We repair equipment, we didn't make the fuel or engine but we sure do catch the wrath of many irate people.

That's why I wanted to write this follow up to my former BS Tip on fuels. Just to drive home the importance of keeping fresh fuel in your engine. If you don't want to heed the advise, that's fine with me, we make money fixing things, heheheh. Just don't go blaming your local repair shop for your failure to maintain. The first weekend of the month, dump the left over fuel in your re-fill can into your (don't do this if your cars engine is diesel) cars tank, use it up before it turns on you. Start the month with fresh fuel in the refill can. For prolonged storage, click on "Winterizing" in my "Back Pages" index.
Happy Mowing