Have a truck maintenance question for Mike? Ask your question.
Mike may look like our mascot here on Facebook, but he’s the real deal at Ten Four.
Mike has been working on heavy trucks and trailers for over 30 years, starting in 1992 as a U.S. Army Heavy Wheeled Vehicle Mechanic.
After the Army, he continued his career in civilian shops, repairing everything from reefer units and bodywork to brakes, suspensions, and welding.
Every week, Mike’s answering YOUR questions about truck repairs and maintenance on big rigs. Straight talk from someone who’s spent many years under the hood.
Check out Episode: 1 now and remember to ask your questions every Monday! Tune in every Thursday for the answer!
Thank you Rich N Jenn for your question: “Hi Mike, is there a difference between running premium as opposed to #2 diesel for gas mileage or for performance?”
“Ask Mike” Questions & Answers
Q: “Is there a difference between running premium as opposed to No. 2 diesel for gas mileage or for performance?” - Rich & Jenn
A: “No. 2 is the most basic diesel out there. It’s the one sold at truck stops, gas stations – everywhere. It meets the bare requirements of the lubricants and the additives. It’s going to give you decent fuel mileage, but premium will be better. There are more additives, more detergents, it burns cleaner, and will hopefully give you better fuel mileage.”
Q: “Why are their air bags under the chassis of the truck? Also, is the cap on the brake drum supposed to be open or does it matter?” – Jamarcus H.
A: Those airbags under the rear are part of the suspension. They keep the truck riding at the right height, which keeps the driveline angle where it should be and helps with control when you’re loaded. They also smooth out the ride a lot better than just leaf springs.
That little cap on the brake chamber is there to keep dirt, water, and road salt out. If it’s missing, all that stuff gets inside and can ruin the diaphragm, and then you’re chasing brake problems which can leave you sitting on the side of the road.
– Mike
“How much diesel does an APU use per hour compared to how much the engine uses while idling?” – Da S.
A: Over a 10-hour period, a truck idling can burn close to 10 gallons of fuel, while an APU will usually use around 3–4 gallons in that same time. Big difference in fuel savings over time.
– Mike
“Which do you recommend: boxed DEF or Pump DEF?” - Amy L.
A: Pump DEF is definitely more convenient, but the downside is you don’t always know how clean the bulk tanks are. Any contamination can cause problems in the aftertreatment system, and those repairs aren’t cheap. Boxed DEF takes a little more effort, but it’s usually the safer bet for purity and can save us a lot of time and money down the road.
– Mike
“Is there a way to prevent DEF systems from clogging so much?” – Enoch R.
A: Enoch, you’re right — the DEF system can be a headache if it’s not taken care of. The best way to keep it from clogging is proper aftertreatment maintenance. If the truck calls for a regen, do it as soon as you can — that helps keep soot levels down. And make sure the DPF is cleaned every 250,000 to 300,000 miles. Staying on top of those two things goes a long way in keeping the system from giving you trouble.
– Mike