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[quote=Anonymous][quote=Anonymous][quote=Anonymous]Dear OP, thank you for all your good contribution here thus far.

I've seen some posts here about 10-min drives, car not warming up sufficiently and related consequences. I'm my case, I do a lot of short drives as well, approx 10 mins, but after around 3 mins (at least in this heat, takes longer in winter), the water/engine temperature needle is approx in the middle, indicating that engine has reached normal operating temperature. Now, for the remaining 7 minutes driving at normal operating temp, does that count as "regular" driving enough to (contribute to) get the water/vapors out of exhaust pipe, gasoline particles out of oil etc, or no?[/quote]

Ok, so there’s “warmed up” according to the light on the dash or the temp gauge, and there’s “warm” as defined by other things.

When the temp light goes out or the gauge shows warm, that’s the coolant temperature. That’s important for things like mixture control, emissions stuff, and various other things that the ECU controls and needs a warm engine to operate efficiently. But there’s some other stuff that requires a warm engine, stuff related to the oil and keeping the oil clean.  So basically, every time a cylinder fires while the engine is running, there is a thin film of burned gasoline residue on the side of the cylinder wall. As the piston comes up to complete the exhaust stroke, the piston rings are scraping this microscopic  residue off, and it gets caught on the rings. And then during the next intake stroke, as the piston bottoms out in the crankcase, the oil bath coats the rings and washes off this residue. Over time, this is what makes the engine oil turn from  clear golden to opaque black. All the burned carbon residue from the firing cycles, scraped off by the rings, and washed into the oil. But it’s also got other stuff in it too. Mostly hydrocarbon chemical liquid compounds that didn’t burn in the firing cycle. This stuff is accumulated in the oil, too. Unlike carbon, it’s a volatile chemical, and can evaporate into a gas over sufficient time and temp. Which is good, because the stuff is sometimes corrosive to some components in the engine, can cause varnish to form, or gun up oil passages. So it’s good this stuff evaporates and cooks out of the oil. But the oil has to be hot to do this. Hot, for a while. And the engine has to be running to route to these gases produced by the evaporating nastiness into the PCV system, which sends them into the engine fuel air charge, into the cylinder, where it is burned and eliminated. So that’s why you need things to get warm, and stay that way for a while like on a long drive. It helps clean the oil

As for the exhaust system... sometimes in winter, you can literally see streams of water pouring out of the exhausts on some cars. Ever see police cars that are sitting in one spot for a long time in the winter? Sometimes they’ll actually have icesickles hanging off the exhaust tip. In cases like that, low rpm or idling, the exhaust is never going to get hot enough to dry out. On a high speed drive, like a highway, it will. But neighborhood driving or crawling along in traffic, won’t get the engine to work hard enough to burn enough fuel to get the exhaust temps up all the way to the tailpipe. [/quote]

Thank you!!! :-)[/quote]

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