Extended life coolants offer reduced maintenance requirements and cost-savings. While conventional antifreeze must be changed every two or three years, heavy-duty extended life coolants last around six years-or 600,000 miles or 12,000 hours of service-with a one-time extender put in at 300,000 miles.

However, changing a truck that uses conventional coolant to extended life coolant can be expensive, requiring you to drain up to 12 gallons of current coolant from your tank, then refill with the extended life version. This is because although extended-life coolant is compatible with conventional coolant, mixing the two reduces the benefits of the extended-life. If a mixture has more than 10 percent conventional coolant, it's recommended that it be maintained as a conventional system.

Shell recently introduced a kit that eases the conversion. You add one gallon of ROTELLA® ELC Conversion Fluid, an ethylene glycol/water-based corrosion inhibitor, to an existing 12-gallon fill of conventional antifreeze.

Shell's kit, which retails for around $225, contains enough conversion fluid for five trucks. It also has test strips, to ensure the quality of coolant before conversion, and sample bottles with mailers that you send off to Shell for testing to ensure the conversion was successful.

Fleetguard offers a similar conversion fluid, the ES OptimaxTM, as does Old World Industries, which calls theirs Final Charge®. But Shell is the first company to package their organic additive conversion fluid with test strips and the support of a post-conversion testing method.