It's always a good idea to add stabilizer to any fuel you use in gas-powered outdoor power equipment.

Peter Sawchuk, the program leader in our Technical division who specializes in outdoor equipment, says a fuel stabilizer will not only extend the useful life of gasoline but also help maintain its performance. "New formulas of gasoline are more prone to degradation and can degrade within a month if not stabilized, outdoor-power-equipment companies are telling us," says Sawchuk.

It's especially important to use stabilizer during extremely hot periods. "Hot weather accelerates the normal degradation of gasoline," says Sawchuk, who also suggests you use a no-spill gas can. A "no-spill can will prevent overflows that evaporate—which is worse for air quality than actually burning fuel—and save you money to boot," he says. Based on past testing of no-spill gasoline containers, those with a manual control to stop the flow of gas typically worked better than those that are supposed to stop the flow automatically.

And remember to keep your mower or tractor running smoothly with some basic midseason maintenance.

Essential information: See our Lawn & Garden Guide for reviews of the best yard equipment and money-saving makeovers for your outdoor spaces. If you're in the market for a new mower or tractor, use our free buyer's guide and refer to ratings of lawn mowers and lawn tractors and riding mowers (available to subscribers).