"Any summer diesel engine maintenance check must include a look at your coolant levels," says Burlingame. "Coolant generally needs to be changed annually, but during the summer, it often needs topping off to keep your truck running cool. All diesel engines run hotter than gas-fueled ones, so many drivers switch to extended-use coolants. The major diesel manufacturers, including GMC/Chevy Duramax, Ford Powerstroke and Dodge Cummins, build engines designed to take the heat, but older models may need coolant additives to get the same performance."

Burlingame adds that older trucks may also need fuel additives during the summer to optimize fuel efficiency. "Older equipment, including engines that run on agricultural diesel, ran on fuel with more lubricity and higher cetane content. When federal regulations made low-sulfur diesel fuel a requirement, engines ran cleaner but initially suffered from inconsistent fuel efficiency depending on the service station's fuel blend. Engines built after 2006 don't have that issue and deliver fairly consistent performance, but check with your diesel engine maintenance team to see if your older engine needs a fuel additive."

Tires also suffer from thermal breakdown on hot roads in the summer. "You want to rotate your tires frequently to equalize wear, but that's even more important in the summer when your tires are more susceptible to wear," says Burlingame. "Aim for a rotation every 6,000 miles if you haul light loads and every 5,000 miles if you carry heavy equipment."

"Summer may be half over, but it's never too late to get your truck in better shape," Burlingame says.

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