PSA: I stopped idling to warm up diesels and my fuel savings shocked me

Most guys in the shop swear by a long warm-up, but I drive gently from cold start. After a year, I cut my fuel use by 15% with no extra wear.

3 comments

3 Comments

ivanm681mo ago

Disagree completely here. Warming up a diesel is crucial to get the oil moving and protect the engine. Jumping in and driving cold can cause real wear on turbo bearings and piston rings. That fuel savings means nothing if you're buying a new injector pump down the road. Old school mechanics have been idling for decades for a good reason.

derek9351mo ago

You're spot on about old school mechanics idling for a good reason. I've seen too many diesels get hurt from cold starts (my uncle's truck comes to mind, honestly). Letting it warm up just makes sense for the engine's life, even if it uses a bit more fuel. That wear on turbo bearings and pistons is no joke, and fixing it costs way more than saved fuel. So yeah, idle on, I say.

stella_roberts9d ago

Watch a modern diesel's oil pressure light. It goes out in seconds, not minutes. That oil is moving. Driving gently under light load warms the engine way faster than idling ever could. You're just burning fuel for no real benefit and glazing the cylinders. The old school advice is for engines from the 80s.

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