There's been a lot of attention paid lately to engine problems driven by new, more complex equipment developed to meet emissions regulations. Sometimes the most basic systems get overlooked because they aren't part of the new technology-driven dynamic.

Yet the function of more complex - and costly - systems relies on basic systems for support.

Take the air system, for example. The compressor/air drier combination hasn't changed, but the 2010 engines use air to drive diesel-exhaust-fluid pumps.

"You can't afford a problem with the air system anymore," says Clint O'Neill, a Detroit Diesel certified product trainer at Pacific Power Products in Ridgefield, Wash. "The oil and water has to be filtered out of the system, because a huge percentage of the aftertreatment system's problems are actually failures of a primary system like an air drier or compressor."

John Wensel, president of Wensel's Truck & Trailer Repair in Spring City, Pa., says compressors and air driers are among his top five reasons for road calls.

That begs the question: What are those less-than-pristine air systems doing to DEF pumps and automated transmission air systems?

In addition to stocking plenty of air compressors and air driers to be ready for customers experiencing failures, help educate your customers.

Suggest, or help them outsource, getting on a maintenance schedule that's appropriate for the climate and operating conditions. And make sure customers know where the air tank drains are located. Often they are hidden behind a skirt or fairing, but they still need to be drained regularly.

If you're selling jugs of fuel conditioner, you may do customers with newer trucks a favor by letting them know it might not be the right strategy if they have a high-pressure common-rail injector system.

"We're seeing problems with emulsifiers in fuel," O'Neill says. "The old school taught us to use an emulsifier to disperse the water and let it pass through the fuel system and the injectors. With 30,000 psi to 36,000 psi fuel pressure and the incredibly tight tolerances in the fuel pumps, we can't have water getting into the fuel system. That's why most of today's engines use sophisticated water separators. The fuel additives allow the water to pass through the water separators without being separated."

Water can wreck a high-pressure fuel system, he stresses. "Do not put emulsifiers in your fuel."