Idling Inquiry

RV Clinic Experts Ken Freund and Jeff Johnston

Q: Something I’ve not seen in your column: Idling. Back when I was a kid (and there was a war going on) I remember that my dad warned me not to idle a car very long because unburned gas would bypass the rings and pollute or thin the oil. A lot of decades later I’m wondering if this still holds true. Is excessive warming of an engine on a cold morning, or leaving the engine running to use the heater while waiting for my wife while she’s shopping, causing any problems? There have been a lot of advances in metallurgy over the years and I’m assuming rings should be better.
Ray Jordan, Colorado Springs, Colorado

A: You’re right, Ray, things have changed a great deal since you were a kid, but that doesn’t have much to do with why a vehicle should or should not be idled for long periods of time. Combustion blow-by happens with almost any vehicle vintage and wasn’t just for old cars. For today’s modern engines with precise electronic fuel controls, wasting that fuel is the worst side effect of too much idling, especially during cold weather. An old carbureted engine could “load up” due to running rich at idle, but today’s engines just meter the fuel down and use what they need. If you need to wait a long time for your wife, I’d suggest going inside the store rather than sitting with the engine running.
– Jeff Johnston


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