Long Live Your Diesel
Yes, diesels get better fuel economy. Diesel fuel has more energy per unit volume than gasoline. The diesel engine also turns more of that fuel energy into force than a gasoline burning engine. The explosion in a diesel engine is longer and steadier than the gasoline engine’s short burst of power. Result; better fuel economy.
Does a diesel engine inherently last longer? This is something I am not sure about. Realistically I would say a diesel engine will last longer only if it is made to last longer. Many people will point out that the diesel tractor trucks on the highway go millions of miles. One must remember that they are engineered very specifically for how they are used. The companies or people that own them expect that from them.
The light duty diesels in one ton and smaller trucks and cars are not designed for long haul trucking and as such probably do not offer the same expected longevity. Because the diesel purchasing customer might expect a diesel to last longer they may be built to last longer. When you tick the diesel option you are always paying more than the gasoline engine option. Is a diesel engine more expensive to build? Again, I am not sure. They might be built better because the manufacturer wants the diesel version to last longer because they expect that is what the owner thinks he/she is buying.
At my shop it is always clear what makes any engine last a long time. The ones that last the longest are the ones that are cared for the best. That includes both maintenance and use. It seems as if it is as easy to destroy a diesel engine as it is a gas engine. Run them out of oil and they will self destruct readily.
If you buy a diesel vehicle it does have some different maintenance issues than a gas engine.
Clean, water free fuel is a must. Diesel engines require special fuel filter media and water separation. Whereas a gasoline engined vehicle may now come with a lifetime fuel filter, your diesel engined vehicle will require a steady diet of fuel filters.
Then there is the engine oil. Diesel combustion produces more soot and some of it ends up in the engine oil. The oil must be able to dissolve a lot more of this soot and keep it suspended in the oil (that is why diesel engine oil always looks blacker). The oil has special additives to help keep the soot in suspension.
Remember also that your diesel vehicle has a lot more than just an engine. All those parts and pieces are the same as any other vehicle. Shocks, struts, brakes, and steering components all wear out. They don’t care if the engine sips diesel fuel or slurps gasoline.