Why You Should Never Warm Up Your Car

[nemo]

Engine oil dilution. It turns out, while you might have thought that letting your car slowly warm up was reducing wear and tear, all that idling time leads to raw gasoline seeping into the oil, breaking down the oil's lubrication properties and increasing the wear.

From here:
Is Warming Up Your Car Bad? - Why You Should Never Warm Up Your Car in Winter

Another reason. not to warm up.

[oil pan 4]

That's why I use multiple block heaters.

[MobilOne]

I don't believe him. I think modern cars do not inject so much gas into the engine as he claims. Now, do I warm up my car before I drive it? No. But I live in GA. If I lived along Lake Superior and it was 20 below, I sure as h would warm it up some. Besides the gas that gets into the oil evaporates and is burned.

[oil pan 4]

I had an old 1885 2.8L v6 chevy that had 2 injectors on the number 1 cylinder. It was there to richen the exhaust to get the converter up to temperature. A waste of gas. I unhooked the power to that injector and gutted the converter. Got 2 to 3 mig better in the coldest of winter. I would get as little as 14mpg highway on the coldest days.

[nemo]

Most cars and trucks today don't need to be warmed up from a a drive-ability stand point. It's my belief that it is done for cabin heat, just as in the south they are left running to keep it cool. While we can't determine how much wear is created by the fuel enrichment and additional running time there is obviously some. Just as which engine has more wear a lower mileage car driven in the city or a higher mileage car driven on the highway.
Is oil dilution reduced in modern vehicles absolutely, I'll bet the management system doesn't forget to remove the choke (an antiquated method of fuel enrichment by reducing air flow.).

[oil pan 4]

Too much fuel can also glaze cylinder bores.

[Xist]

Crazy Ex said she needed to let the Forester warm up for some excuse that did not matter to me. I responded the best way to warm up an engine is by driving it, which I read here

[me and my metro]

Some modern "clean" Diesels inject fuel on the exhaust stroke to heat the cat to burn the soot in the exhaust filter. This regen process works fine if you happen to be driving on the highway. I work for an electric utility and this system has caused a lot of problems when the regen process gets interrupted. Our trucks often run at low speeds and run a power take off to power the boom. The regen process only runs while driving. Unburned fuel ends up in the crankcase diluting the oil. That and all the high pressure fuel system is under the valve covers, if something leaks it stays inside. The oil capacity is 15 quarts and we have to monitor oil level for over level. We have drained as much as 25 quarts of diluted oil from these trucks.

[redpoint5]

I'd pull the DPF off depending on what county you have the trucks registered.

[me and my metro]

We serve 6 western states, our trucks stay 50 state emission compliant.