Don’t idle those diesels

Hi Sir Lord!  I read your article about modern diesel engines while trying to research on my new purchase. I bought my first diesel car recently. It’s an (sorry, can’t name the brand) SUV and I enjoy driving it as it feels much powerful than our daily car, a 1998 (brand). It was even gas powered.  We also feel safer because its bigger.  The engine is also very responsive and it is very fuel efficient, I can wait for Mrs. outside the parking lot with Aircon ON.  I would like to know if there are any different procedures to observe in owning a diesel car. For example, do I need to warm up the engine before running, and why can’t I turn it off directly after a long drive? From JD

Hi!  First of all, congratulations on your purchase. 

A modern diesel SUV is nowhere near comparable to a gasoline powered sedan, especially ones made in the late 90s. For one, almost all SUVs use a modern turbo diesel engine, producing so much torque. It can go up the mountain highways with ease with seven people on board. 

Modern diesel engines are no longer noisy or rough, retarded and smoky, like its past reputation. This is because of the latest breakthroughs in diesel engine technology. The precision of electronic fuel management, the efficiency of direct fuel injections and the power of the modern turbos coupled with the advancements of the engine itself have made the new diesel engines popular not just in SUVs and Pick-up trucks but also in cars. 

Modern turbodiesels, as what we call it in motoring media world, are not just fast and smooth, they also emit far less pollutants compared to before. You just have to make sure you get your diesel in a reputable gasoline station. I have heard horror stories of engines stalling because of dirty diesel fuel from less known gas stations.

The service interval for diesel models is often not the same as for petrol cars. Although diesel might be more fuel efficient than gasoline powered ones, it also requires much more TLC.  This is because diesel fuel is so much more unrefined. It tends to form more gunk in the engine. Diesel engines use engine oils which may have different viscosity or require different additives and detergents. To keep your car in good shape, just follow the maintenance routine specified in the owner’s handbook. Also, your authorized dealer should be aware of this.

The procedures for operating a modern diesel differ from manufacturer to manufacturer but doesn’t fall far from how gasoline powered engines are used. Modern diesel engines need not be heated before operated. Idling for a minute or two prior to shut off is not because it’s a diesel engine but because it’s turbocharged. Turbos glow with heat in long trips and it’s wise to let the coolants/oil flow through it for a while before turning it off to avoid cooking the oil or coolant.

But unlike petrol engines, which operate on a very narrow band of air-fuel ratios and can’t run lean with load without stalling, the diesel engine can operate in variable mixtures. Thus, when idling, modern diesel engines can run lean and burn very little fuel without the risk of overheating. This is probably why some drivers do not bother switching off the ignition while waiting.  This I highly discourage though, as idling in parking lots will add to our CO2 levels.  Might be even illegal - check our laws.

So even if the new SUVs feel as cozy as your living rooms, turn it off and help your Mrs. with the groceries. You’ll be helping the environment plus those extra hundreds of steps is a good exercise.