DON MILLS, Ont. – By now there’s a chill in the air and folks who live high enough in latitude, or altitude, will soon be seeing the white stuff.

Soon temperatures will plunge and so will truckers’ confidence in how their fuel will behave. Will it flow well enough to get through the lines, and remain sufficiently clear to get through filters?

Many operators use fuel heaters, but in especially cold climates fuel additives can help, too. In cold weather we think of additives as compounds, which keep fuel thin so it flows and clear so wax crystals don’t form.

Of course, fuel additives can also inhibit the formation of fungus and bacteria in warm weather.

If your trucks run in really cold temps and your operation sees engines shut down often, fuel can get cold enough to run into problems, even with heaters aboard. So additives might well be on your shopping list.

There are many good products on the market and most do what they say. The important thing is to use any product according to instructions. If too little or too much additive is mixed with fuel, it may be ineffective or cause engine damage. If you’re a driver entrusted to pour in additives during fueling on the road, read the instructions on the label and add the correct amount.

It’s human nature to think that if a little is good, more is better. It ain’t so in the case of additives.

Many fleet managers consult with engine builders and determine beforehand what products are acceptable for their engines. Then they either send cans or jugs of the stuff along with drivers, or tell drivers what products are approved so they can buy the right stuff. That list should have more than one choice because the favorite product may not be available everywhere.

Some products on the market might do more than what their makers say. That’s why, aside from asking engine builders, the wise fleet buyer asks some pointed questions to would-be vendors. In its Recommended Practice 312, the Maintenance & Technology Council of the American Trucking Associations (ATA) lists 10 questions that probe the content of fuel additives.

Will the additive reduce a fuel’s cetane number?

Cetane is a measure of a fuel’s ability to start on a cold morning, so should not be cut (some additives claim to boost cetane numbers).

Will the product increase ash content?

Ash in Number 2 diesel should not exceed 0.01 per cent by weight. How much additive will it take to reach that level?

Does the additive contain any metallic or halogenated compounds?

Some metallics can be beneficial to combustion, but find out exactly what they are and how much is in the product. Halogenated compounds, including chlorine, flourine and bromine, can form toxic acids that attack engine parts.

Will it increase the fuel’s vapor pressure or flash point?

If so, there’s an increased fire hazard.

How does it affect the fuel’s viscosity?

If the fuel is too thick it may not burn right; if too thin, it may not lube the pump and injectors.

Will the additive combine with and suspend contaminants, carrying them to the filter and plugging it?

Will it stay blended with the fuel or settle out?

If it settles, it no longer does the fuel much good.

Will it reduce the fuel’s cloud point (the temp at which wax crystals form)?

Some products claim to; ask for proof.

Will it reduce the pour point (where fuel begins to thicken prior to gelling)?

If so, by how much?

If too much of the additive is added to fuel, what will it do to the fuel, and to the engine?

You might add an 11th question: What will this additive do to exhaust emissions? Authorities at various levels are getting serious about checking exhaust smoke, and some have equipment that analyzes what’s in the exhaust. Heavy metals and other ingredients in an additive can affect exhaust, and who knows if a citation will result?

A 12th question will come up when you get your first diesel with exhaust gas recirculation (EGR): How will this additive impact the engine’s EGR equipment, and how will it react to exhaust gas in the combustion chambers?

Sometimes the product’s label will answer questions. If the supplier is reputable, the label will be accurate. Read it. If the label gives no answers and/or says little about the product, don’t buy it.

Now, if it’s 40 below and a 35-mile-an-hour Manitoba wind is whipping through the truck stop lot, few drivers are going to stand at the pumps and read a label. If they’re not familiar with a product, they should take the container in the cab or read the instructions before leaving the store.