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Originally Posted by Lil bastard
Wear occurs at startup - 85% in a 'normal' engine's lifetime. But not because the oil isn't warm, because all the floating parts - crank, cam aren't floating and because the other metal parts experience metal-to-metal contact until oil flows to float and/or coat or 'film' the other parts.
The question you pose isn't ąperpot. It isn't a question between these things at all. You either experience normal startup wear alone,... or you add to it the effects of inefficient combustion on your catalytic convertor and the adverse effects of reduced flow of coolant and oil to the engine - the first is unavoidable (unless you have an electric pre-luber), but the second is totally voluntary.
Cheers!
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I agree, I believe most of the wear occurs within a few seconds of startup and without a preluber system it is unavoidable. It can be minimized with a low viscosity multi-grade synthetic oil, but not eliminated. I personally let my cars warm up and idle for several minutes if it is sub freezing. The colder it is the longer I let it warm up and idle. Under a cold start in those conditions the car's ECU sets the idle higher, usually close to 2,000 rpm for awhile to get the oil pumping and engine warmed up faster I assume. This may be all wrong and pehaps I'm making things worse for my engine and exhaust system, but it makes the most sense to me so I do it, plus it's no fun getting into a freezing cold car. In regards to let it idle or not, in the end it probably doesn't matter much either way, people have their preferences and there is no clear right or wrong answer. I do think some of the push to drive off right away comes from the "green" camp who hates car emmissions thus can't bear to see a car idling away doing nothing but polluting the air. I believe this line of thinking has influenced the mainstream and "car people" alike.
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Originally Posted by mikefocke
if, instead of sitting idling at 800-1200RPM, the engine and transmission were operated below 2500 RPM as you drive for the first few miles?
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This sounds good in theory, but if you shift at 2,500 rpm then you are putting the engine in a very low rpm range essentially lugging the engine some which is a no no. The rpm difference between 1st and 2nd gear is about 2,000 rpm so shifting from 1st gear to 2nd gear at 2,500 rpm would drop the revs to aprox 500 rpm. Just playing the devil's advocate maybe, but it seems a lot of people are splitting hairs on this subject so I figured I'd throw that in there.