Warm Engine Before Driving

As was mentioned, warming the engine for a few minutes is a good thing and something you should be doing anyway during the pre trip to listen for potential air leaks as well as allowing the engine to get up to operating temperature. In regards to idling, it will absolutely Not harm these engines. What excessive idling will cause issues with is the emissions systems but a few minutes warming it up in the morning before you leave isn't going to have any effect on that. (I could write another thread on the things being done that does have negative effects on the emissions systems but I won't include it in this thread)

What excessive idling will cause issues with is the emissions systems

I've noticed that more during the winter season when you pretty much have to idle to not freeze your fuel. Wake up in the morning with a check engine light, diagnostics saying a problem with the emissions systems. But my issue was also related to something about the EGR valve(?)

I have received conflicting information. Some say don't warm up the engine before driving but move slowly for a few minutes. This method is not practical when I am leaving a rest area on the Interstate. Some people tell me to wait until the coolant temperature is at operating temperature. Which is the right way?

I suggest you ask your company and then do what they say - it is their truck.

My company told me that recent model year trucks no longer need a warm up phase regardless of weather. If/once you have adequate air pressure for brakes and auto trans (if applicable), you are good to go. When it is cold out (like under 20), then run your optimized idle, or some kind of idle (whatever you have) to keep DEF and fuel from freezing, as well as to keep batteries charged if you do not have an APU.

Conflicting advice abounds - but what the owner of the truck wants should govern. If YOU buy a truck, then do what the manufacturer of the truck advises.

Interstate:

Commercial trade, business, movement of goods or money, or transportation from one state to another, regulated by the Federal Department Of Transportation (DOT).

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

"When it is cold out (like under 20), then run your optimized idle, or some kind of idle (whatever you have) to keep DEF and fuel from freezing, as well as to keep batteries charged if you do not have an APU." - David Reid

I lived in Georgia through a winter. I would get up in the middle of the night and find that the girlfriend or kids left the faucet on. Then I would make it to the kitchen and yep the darn faucet is dripping. It had to be explained to me that's what you're supposed to do! I'm from South Florida and clueless.

Now you're telling me that the fuel and DEF can freeze. So when the forecast calls for temperatures to be at 20 or less, I need to keep the truck running?

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

"When it is cold out (like under 20), then run your optimized idle, or some kind of idle (whatever you have) to keep DEF and fuel from freezing, as well as to keep batteries charged if you do not have an APU." - David Reid

I lived in Georgia through a winter. I would get up in the middle of the night and find that the girlfriend or kids left the faucet on. Then I would make it to the kitchen and yep the darn faucet is dripping. It had to be explained to me that's what you're supposed to do! I'm from South Florida and clueless.

Now you're telling me that the fuel and DEF can freeze. So when the forecast calls for temperatures to be at 20 or less, I need to keep the truck running?

Yes. Reread Dave's reply. It's copied at the top of your reply.

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

Forgive me for being dense. But how does running the engine keep the fuel & DEF in the tanks from freezing?

Heat from the engine, just enough to reduce the tendency to gel. Fuel flow through the line also helps. Most fuel is treated with anti-geling agents that work well to a point.

When temp is close to zero we get a fleet mssg at the D.C. to keep the motors running.

In cold temps, my bunk heater also keeps the engine from getting completely cold, so when I start my truck, it's got a bit of a head start on warm-up.

DEF will freeze, but causes no problems. The heat of the engine will thaw it out. I believe the are "heaters" installed, or just the way the lines are routed.

Fuel will definitely gel in the winter, and you'll be screwed. It's best to use some anti gel just to be safe. Put some in the reefer and truck, then run your bunk heater, truck, and refer to make sure the anti gel treated fuel is throughout the system.

Yeah, they tell us to put in the anti gel if it is 10 degrees or less. But if it is 10 degrees or less, it is best to head south

DEF will freeze, but causes no problems. The heat of the engine will thaw it out. I believe the are "heaters" installed, or just the way the lines are routed.

Fuel will definitely gel in the winter, and you'll be screwed. It's best to use some anti gel just to be safe. Put some in the reefer and truck, then run your bunk heater, truck, and refer to make sure the anti gel treated fuel is throughout the system.