Optimal Engine Temperature for Oil Change: Cold, Warm, or Hot? Comparing Methods & Efficiency

The topic is probably as old as the world, but to find something that clearly explains the dilemmas of many, this is already a problem, most think that it is better to replace it on a warm engine (this is how more than one instruction gives) because, as they think, more will flow, others think that it will be less flowing in a relatively short time (15 minutes) because the engine that has been working a moment ago has oil splashed all over the engine and it must take a long time for it to drain out in the same amount as the drained cold oil. Of course, let's not dwell on engines that are cold to -25 degrees celsius. and oil that has not been changed for 10 years and is so thick that the pan needs to be unscrewed, consider engines in which the oil is changed every 10,000 or 2 years.
Every sentimental owner of some kind of wets care about the flow of this oil as much as possible, some even go so far as to unscrew the bowl together, of course, with the filter, others prefer to rinse the engine with cheap oil and fill it with the right one, others after draining the cold oil start the car for a few seconds - it is not about the fact that the car is started, but the oil pump is moved, then an additional 0.5l of dirty oil flows, after such a procedure, after driving 200 km, the oil is still so clean that it is difficult to see it on the dipstick, I am writing about gasoline here because in deliaslach oil it gets dark in the first seconds of firing, no matter how the oil is changed, although the latter method is moronic for many because they believe that the engine is damaged (working for a few seconds without oil) this engine works in total for more than 5 seconds because it has to draw the oil, for many it does not matter much because the engine always runs dry when starting. More than one changes the oil, draining it, whether it is hot or cold, and floods it, without even replacing the oil filter, does not pay attention to it whether there is something left in the engine or not, after changing the oil in accordance with the instructions (on a hot engine), the durability of the engine does not change, but maybe succumbs?

WHAT IS THE OPINION OF OTHERS AND I AM NOT INTERESTED BY THOSE WHO HAVE NEVER DRAINED OIL AND HAVE NO MORE CONCEPT OF MECHANICS ONLY OF THOSE WHO CAN CREATE SOMETHING AND KNOW ABOUT THINGS.
Maybe some links to interesting articles on the topic would be here?

rekda2 wrote:

others, after draining the cold oil, start the car for a few seconds - it is not about the fact that the car is started, but the oil pump is moved, then an additional 200 ml of dirty oil is drained,

It is unlikely to help. The pump is not a fan, if there is nothing to suck in, it is also not able to push out the oil in the oil channels.

The oil pump is able to (I don't know whether to push it out but) to give the oil back without sucking in a new dose, certainly not all the oil, but about 300 ml.

A friend must be an expert on this and that there are a lot of such people in pl. It's probably not worth fucking with a thorough oil change, it's better to do it more often, but when you buy a used car, you don't have much to choose from, the argument that some SHELLS get in the ass after draining the oil from the pump is rather exaggeratedly written, the oil is sucked in without any serious problems (a good pump for passenger cars, not trucks) because the pump is not dry as pepper after such draining, the time it takes to deliver the oil to the pans is minimal, I suspect that within a few seconds the pans are also not dry as pepper, so although I can be completely wrong . It should not matter when the pump is emptied 1 or 3 times, after all, the bushings are not so loaded at start-up, but I admit that the air sucked in can slow down, and even significantly the possibility of sucking a new dose of oil, especially in cars with high mileage.
I raised the topic because I have no experience and one day I listened to some people discussing it and as I supposed to have some idea about the engine, I was asked to contribute and unfortunately due to the lack of this knowledge, I could only philosophize. Most mechanics will tell you that the oil is changed on a warm engine, but if you ask why on a warm one and not on a cold one, they have one and only argument because the oil is thinner, and my question is whether cold oil is not the same with -20 degrees Celsius only +15 is enough thick that it flows slower? no, it does not run off slower, in addition, the most polluted part of the oil runs off, unlike the hot engine.

The topic may not be worth reading, but there is nowhere like this.

And why on a warm engine and not on a cold one?

NO IT IS the same thing, I think we are aiming for it that it does not matter whether I drain the oil on a cold or warm engine, and it is not true that engine oil should ALWAYS be drained on a warm engine, it should burn, although a warm engine is not always hot.
And this question again, because my colleague does not read from the beginning whether the warm oil from the engine that has just been put out will drain faster than the cold oil in the same amount at the same time !! ????? e.g. 15 min.

When you flood some 20w50 crap from the 80s and try to change it in winter, I am not surprised that you need to warm it, because this jelly, even in light winter, does not want to run off at all.
In the age of synthetics, such a topic should end up in the basket long ago.

That's it !! And I am surprised by the claims of mechanics that engine oil is always changed on a warm engine.

'' Modern oils, thanks to the strong dispersion properties of soot particles, sludge, sludge, varnish, etc., allow you to keep the engine perfectly clean ''

Unscrew the valve cover in the engine in which the oil was regularly changed, with not high mileage - what IDEAL dispersion properties can you talk about then ??? A PURE THEORY that has little to do with reality, even writing about gasoline engines.

How long does it take for these particles to start precipitating from the oil 3h, 8h, 24h or several weeks or even months, or immediately after cooling down, ???????

'' By draining the cold oil, e.g. after a night in the garage, you drain the oil with less dirt because some of it precipitated out and was left in the engine ''

So what has this part of the pollutants evaporated and deposited in the channels and tubules?
rather, it is only in the sump and it is in the place where it contacts it that there is a possibility that these impurities will remain.

Dear reader, with the greatest respect for you, but you present some old, as you admit, book and some theory, maybe partly logical, in the description you write about modern oils, does it make sense ??

I had the opportunity to change the oil a few times and maybe I did it incorrectly, but I drained it on a cold engine and not because I could burn myself on a warm one, but because I was convinced that it is better.

The topic may be stupid, but the current arguments do not reach me, and this is because arrogance appears here.

Be consistent in what you write and read, and if you can't do it for elementary school, as at the beginning I wrote to express something, have your imagination! just what does that have to do with this?

Several statements

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Well, I read a lot of information on just changing the oil, in the automotive press, so they probably know what they are writing and that's where they pointed out that treating a hot engine with cold oil can damage the head ... Of course, it is known that this does not always happen, because they constantly replace yes, oil in service stations and nothing ... But when you read it carefully, you can notice many statements like "they changed my oil, and after leaving the site after a few kilometers, the engine suddenly stopped and went out" and in many cases the expert opinions showed damage heads ... But it is like washing car windows in winter with warm water - they say they break, I also did it several times this winter and ... the windows of the entire Applause
One thing is for sure - changing the oil yourself and waiting for the engine to cool down is the best Applause solution
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'' A few such "exchanges" and at the bottom of the bowl you will have a nice swamp - see how much oil they suck with this method in relation to how much they should - 1/3 is left, and that's the worst sludge. Pouring cold oil into a hot engine causes surface stresses in parts that are rapidly cooled down and their thermal deformation, mainly the camshaft (because it is most often directly under the filler)
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When I add oil to a cold engine (Fiat 1, oL fire) and even after 30 minutes I go, the oil pan seal is blown out. In this case, the oil clogs the pneumothorax. by pneumothorax without clogging it (pneumothorax channels and oil drainage from the camshaft pass through the engine block). The engine cools down quickly and 15 minutes after turning the engine off, its temperature is much lower.
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It all depends on the engine and its correct (well-thought-out) design ... I have been pouring oil for 3 years only when the engine (sixteen-valve) is completely cold and there have never been problems with clogging pneumothorax ... it had a much lower temperature ... besides, as I wrote in websites or workshops, they do not wait even these 15 minutes, they only pour cold oil directly into the hot engine ...
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First, the vacuum sump emptying method may not be as accurate as the traditional method, but very little oil remains, around 30-40g. This amount is much less than 1/3 and has no significant effect on the condition of the fresh oil. More than once I have emptied the bowl in this way to then disassemble it in order to, for example, replace the gasket so my words may be credible.

Under the second, in a regularly serviced car, you will not find any sludge in the sump - the oil is homogeneous. The pump head is located just above the bottom of the pan, so the oil circulation in the system is very good. Any impurities remain in the filter

Third, thermal deformation of the camshaft is impossible. The shafts, like the crankshafts, are made of hardened, low-alloy, heat-resistant steels. At most, the camshaft may break. It is not possible to bend, deform. When pouring cold oil, usually elements made of less thermally resistant materials - mainly aluminum heads
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It is true with this cracking of the cylinder heads due to the addition of oil on a hot engine, for example in the BMW M20 engines. As for sucking oil - there are engines in which you will suck more oil than you can drain with a plug, e.g. matiz. When I change the oil in my own, I usually unscrew the cap and filter in the evening and pour oil in the morning.
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It is worth knowing that the damage to the shaft is usually the result of an earlier damage to the engine or, what happens most often, of improper condition of the oil. The working conditions of the camshaft are much heavier than the situation when we pour cold oil into a warm engine

Dude, I have been on the forum for a short time and I noticed that you enjoy a lot of authority here. Reading the archive I must honestly admit that your knowledge is great and you have helped many times. And a lot of respect. But it also irritates me that you try to fill the gaps in this knowledge with your imagination. Please keep that in mind.
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Hello gentlemen.
I will not talk about the oil suction, but if you write so wisely, I would like to note something:
1. The shafts are rather made of high-alloy steels, structural steels are low-alloyed ...
2. With increasing temperature, the dimensions of the material change, but with this type of elements the expansion is negligible, otherwise the engine would wear out quickly
3. The shafts at issue have such a high hardness and low plasticity that they break most frequently and deformation is rare
4. Shape change due to poor storage is a fact because there is creep, but the camshaft in the sun ?! How many years would he have to lie and in what heat? Well, unless it's a cast iron ...
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does 10% old oil mixed with new oil have better lubricating properties than the whole new oil anyone can find something about it?

as it turns out, some interesting topics have already been discussed

http://honda-tech.com/showthread.php?t=2667258

http://www.irv2.com/forums/f124/oil-change-temp-hot-or-cold-or-warm-100084.html

http://www.classadrivers.com/forum/truck-maintenance/34752-changing-oil-when-hot-cold.html

http://www.suzukihayabusa.org/forum/index.php?topic=58437.0

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1479704

http://www.youtube.com/watch?v=iFtLs8qoq7Y