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Warming up your car before driving in cold weather can damage the engine (2016)

businessinsider.com

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Re: Warming up your car before driving in cold weather can damage the engine (2016)

#162

There is no oil where they claim it in the cylinder on Japanese engines, otherwise they would be burning oil (and they don't). At least not for the first 300,000kms or so. If the fuel can ever burn the oil, that's a really bad thing. Also the article claim about the power steering pump is completely wrong, as the pump runs no matter the speed or load of the pump; it will just pressure-relief through the pumps interna…

Unless it’s so cold that the pressure is higher than the PRV can … relieve.

Same is true of the PRV at the oil filter. If you’re bypassing that, then you’re forcing unfiltered oil into the engine.

Also, a too high oil pressure can wash out the babbitt on main and rod bearings.

Agree that the article is bad.

Wouldn’t say “no oil” as oil control in modern engines is good but not perfect and the rings (above the oil control ring) need some oil.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#163

Earlier quoted context omitted.

Many new cars have electric heaters for the air venting into the cabin. In that case their statement about confusing warm air with a warm engine would be true.

Especially small diesels which take too long to warm up for passenger comfort.

Yes, but the whole argument about washsing the oil off cylinder walls is irrelevant to diesels, as excess diesel lubricates, rather than dries cylinder walls.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#164

Earlier quoted context omitted.

That specifically talks about using the AC, because it's dehumidified air. The AC also requires the engine to be running, so blasting the windshield with hot air or air-conditioned air will require running the engine for roughly the same amount of time.

I don't know about your car, but it takes less than a minute to defog my windows. I don't think anyone is claiming that running the engine for a minute is bad.

Try ice on the inside of your windows.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#165

Earlier quoted context omitted.

sure, but the basic physics at the very heart of the issue (use oil to avoid direct contact between metal pieces) is exactly the same. it seems very unlikely that modern refinements have completely reversed the concerns.

Having a water jacket around the cylinder makes it less possible for the cylinder to heat (and change size) unevenly versus an air(/oil)-cooled engine. That same water jacket permits the tolerances to be set to assume a maximum head temp under 300°F (versus 460°F for airplanes). That means the steel rings don’t have to deal with as much dissimilar expansion as the aluminum heads and pistons. This allows engineers to…

I don't see how water jackets, pistons rings, and their tolerances are directly relevant here. The topic was bearings, and their lubrication and wear, in the larger context of warming up your car before driving in cold weather.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#166

Don't listen to this nonsense as it's absolute baloney. I would ask the experts that design engines and oil rather than a one-off op-ed piece from a news source with a questionable reputation, a history of sensationalism, and zero applicable scientific qualifications. The primary reason you warm up your engine is because oil is more viscous at cold temperatures. All engine oils have cold flow characteristics and modi…

Modern synthetic oils are plenty viscous at subzero temperatures. Warming your engine isn’t necessary in a modern vehicle beyond taking it easy for the first 5-10 min of driving.

(Nor will it appreciably decrease your engine’s lifespan.)

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#167

Earlier quoted context omitted.

I love how the examples are always Alaskan winters but you see people idling their car to warm up everywhere and often in moderate temperatures. For most, it's a comfort thing and not necessary.

If you're even using a car at all, then you have already decided that comfort and convenience are necessary.

Let's not make the perfect be the enemy of the good.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#168

Earlier quoted context omitted.

I love how the examples are always Alaskan winters but you see people idling their car to warm up everywhere and often in moderate temperatures. For most, it's a comfort thing and not necessary.

If you're even using a car at all, then you have already decided that comfort and convenience are necessary.

Ah yes, a two-hour commute to work is just a minor inconvenience. One should ride a bike in such circumstances.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#169
post #128
post #127

Earlier quoted context omitted.

> If you are getting more than a super tiny film of oil in the cylinder, you’re burning oil because your rings are toast. The "cylinder" is more than just the portion where combustion occurs, when the piston is at or near top dead center. The portion the article is talking about is the portion that, as I said in my previous post, is exposed to gasoline when the piston is at the bottom of its stroke--as it will be at…

The cylinder has rings to remove that oil, hence my comment. There should also be very little to no gasoline contacting the cylinder walls at the bottom of the stroke, or at all. The air currents inside rarely directly contact the cylinder walls. If you have any evidence that the effect you’re describing exists, it would be nice if you link to it!

I don't have any evidence either way, I'm simply trying to get clear about the effect the article is claiming. I am not saying I agree with the article's claims. As I have already said, I don't think the claimed effect would be significant if it exists.

Re: Warming up your car before driving in cold weather can damage the engine (2016)

#170

Earlier quoted context omitted.

Having a water jacket around the cylinder makes it less possible for the cylinder to heat (and change size) unevenly versus an air(/oil)-cooled engine. That same water jacket permits the tolerances to be set to assume a maximum head temp under 300°F (versus 460°F for airplanes). That means the steel rings don’t have to deal with as much dissimilar expansion as the aluminum heads and pistons. This allows engineers to…

I don't see how water jackets, pistons rings, and their tolerances are directly relevant here. The topic was bearings, and their lubrication and wear, in the larger context of warming up your car before driving in cold weather.

Imagine a cold-soaked engine with an aluminum piston, steel rings, a cast iron sleeve in an aluminum head. The aluminum piston will heat very quickly compared to the cast iron sleeve in an air-cooled engine. (There’s a massive aluminum heat sink in the form of the cylinder head.)

For a water cooled engine, there is a water passage around 3/16” from the cylinder wall which helps to bring the cylinder up to an even temperature more quickly and prevents a high heat flux from expanding the piston to the point where it can scuff the walls.

It’s not only oil pressure that is a concern for a cold-start to operating temps.

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