Our trials show that Tanis delivers more heat faster, but it also costs more to install. Reiff’s good-enough approach is the top value for most owners.

By Jim Cavanagh

When the temperature dips into the low 20s, everyone we know seems to agree that preheating an engine before starting is a good idea. From that point forward, however, opinions diverge. How much preheat is enough? How long should you run it? Is an electric system better than a propane blower? There are no pat answers. There are a dozen ways to heat an engine from makeshift propane-fired torches to

Pre-heaters, should be capable of heating engine cylinders and oil well above 40 degrees F.

100-watt lightbulbs in the cowl flaps. All of them work, but some clearly work better than others. …