Yes, diesels last longer than gas engines, but it’s mainly due to its manufacturing. A typical diesel engine is bigger, heavier, and has sturdier components to withstand the higher compression ratios. It has beefier camshafts and crankshafts, reinforced bearings, and larger main bolts than a gas engine. Furthermore, diesel engines have a mostly gear-driven design and have fail-safe components for cooling, timing, and other ancillaries.
The sizable internals enable better oil flow, protecting the engine from excess friction during cold starts or heavy-duty applications. Meanwhile, diesels have oil jets that spray oil under the pistons to maintain sufficient lubrication at any rpm.
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But a large part of what makes a diesel engine last longer than gas is the lubricating and cooling properties of diesel fuel. Besides helping to reduce wear and tear, diesel fuel has a lower auto-ignition temperature than gas, and most diesels operate at a leaner air/fuel ratio. And since diesel is more energy-dense than gas, it doesn’t need to spin at 6,000 rpm to produce thrust, with most diesel engines achieving peak torque at a lower engine speed.
The low-rpm properties of a diesel equate to less wear and tear on the pistons, piston rings, cylinder walls, and valves. Of course, no diesel engine would reach 500,000 miles without judicious maintenance. Sticking to the manufacturer’s recommended service requirements is the key to making any engine last longer. When in doubt, refer to the owner’s or service manual to know when to change your diesel rig’s oil, air filter, fuel filter, transmission oil, and coolant.
