Cold engine oil changes...

Skytower

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Draining "hot" will not "flush" anything. It might flow quicker, but not life changingly quicker. You will never get all of the oil, or contaminants, out of the entire engine. I depend more on my filter to get those nasty little particles, more than the oil dragging them out.




And, my point was that the oil that I put into the motor, is not warm, yet it flows very well. In addition the bottle empties quite quickly, and completely. As I said, I've always drained hot/warm. But, Top Ten's questions got me to thinking. . . . :)
I never claimed that it gets rid of all contaminants. It flushes out more of them. Filters are nice, but bypass valves exist because filters get overloaded. That's why it's best to get out as much garbage as practical, with an easy method... like draining directly after a ride.

Glad you have a questioning attitude. Cheers!
 

Jlq1969

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The “normal” oils, from several decades ago, did not have detergents, so it was important to drain them hot, to ensure that all the soot from the combustion was in suspension (due to the heat and movement of the oil), time of drainage. Modern oils (which began to be called hydrogenated), have detergent and dispersant properties, which ensures that the soot particles remain suspended in the same oil and go outside with the drained oil. With these modern oils, if the engine is stopped for a considerable period of time, the so-called "muds" no longer occur, which would occur with "normal oils" ... and which is nothing more than precipitated dirt. at the bottom of the crankcase, because the oil could not contain it in suspension
 

RCinNC

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The problem with answering questions like this is that we have a scarcity of people on the forum who've worked in the auto/motorcycle manufacturing industry as designers, engineers, or legal representatives , and most of these "why do we do it this way" questions could be answered by someone who was part of the design process. There has to be a reason that the manufacturer of every vehicle I've ever ridden or driven recommends that the engine be warmed up before you drain the oil, and the reasons for manufacturers' recommendations for pretty much anything involving our vehicles are either engineering based, design based, or legal based.

I can't see how the manufacturer's oil change routine on a Super Tenere would be either design based or legally based; the design of the engine doesn't preclude changing the oil when it's cold, and as far as a legally based decision, it's objectively more dangerous to change to oil on a hot engine than a cold one, so I doubt that a manufacturer's legal department would recommend a procedure that was more dangerous to the owner unless it was felt to be necessary.

So, you're left with an engineering based decision; some engineer at Yamaha (and every other vehicle manufacturer to my knowledge) chose the warm engine recommendation over the cold engine, in spite of that being the more dangerous way to do it. It could be as simple as "hot oil drains faster". My experience with oil changes is that hot oil from the crankcase drains out a lot faster than cold oil pours in. if this seems in doubt to you, next time you do an oil change, poke a hole in the bottom of your bottle of oil that's the same size as the oil drain bolt, open the cap, and see how long it takes to empty that one quart container as opposed to how long it takes to fill a one quart container of hot engine oil from the sump. They don't flow at the same rate. Engineers tend to lean towards efficiency when left to their own devices, and there's less efficiency in choosing a slower method for a procedure when a faster method will suffice, with all other factors being equal.
 
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Checkswrecks

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I've been working on engines since I was a kid, have worked with most engine manufacturers in aviation and have a Powerplants license and you guys have already hit everything I've learned, been told, and seen in my own tear-downs. The three big reasons to change oil are loss of shear properties (the strength and lubricity of the oil), removal of acids, and removal of combustion contaminates which are mostly microscopic to visible carbon flakes not metal.

Addressing the first two, a hot drain gets the oil to flow faster and being thinner there will be less of the dirty oil remaining. If we had an accident in winter that broke the crank case and then moved the engine into a warm shop, it's amazing how much more oil comes out. It was far worse with petroleum oils in piston engines but still happened with the turbine synthetics.

Oil movement in a running engine does stir up what is laying in all the low spots, including the crank case, head, side covers, etc. Shut down the engine and the silt settles and over time it can collect as sludge. Running the engine to heat it picks up a lot of that and draining while hot means getting those contaminates out before they settle again.
 

jeckyll

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Oil threads are always fascinating :)

Overall, I'd still say it's more important to do regular oil changes vs. almost all other factors (exact right temp, exact length of time etc etc). When in doubt change a bit more frequently.

It's great to see people weigh in that have real experience with engines and have some things confirmed (i.e. keep doing the change on a warm motor when possible :) ).
 

gunslinger_006

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I just send my oil to blackstone and take their input seriously.

You can speculate all day long but a lab test doesnt lie. It always tells you what is happening inside your engine.
 

jeckyll

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I just send my oil to blackstone and take their input seriously.

You can speculate all day long but a lab test doesnt lie. It always tells you what is happening inside your engine.
Please post the results (and riding conditions you went through). Would be very interested :)
 

Sierra1

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. . . . Overall, I'd still say it's more important to do regular oil changes vs. almost all other factors . . . .
That's where I'm at. We all know at least one person that changes their oil, maybe, when the oil light comes on. And, yet their car/bike/truck keeps plugging away. So, I figure, changing my oil when the factory says to, with the oil that the factory says to use. . . . my engine is probably not going to self destruct because I didn't get it, or the other stuff, completely out. Do what makes you comfortable.
 

Xclimation

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I was also taught to drain the oil as hot as one can tolerate not getting burned. But I've changed that many years ago. I'm not going to say I drain it completely cold. But sometimes. I want the oil to settle in the oil pan and drain as much as it can....having said that...we do have a dry sump system in our bikes so that changes the dynamics. One thing to consider is viscosity breakdown. Once the oil gets used, the breakdown causes it to be more thin. Also, I want any particles...(if any) to settle in the oil pan so when I unscrew the drain plug; any particles will drain. But, I'm guessing particles will be in the oil filter. I've been in a few engines of many types throughout the years of many types and have never noticed many particles in an engine that was running properly. I've seen sludge, (especially in my niece's Camaro several years ago and she didn't understand the concept of oil changes...) Seen metal particles in oil from engine that had issues. But I let my oil drain for a good 30 minutes, tilt my bike on the side to try and get more out. I also measure and inspect the oil coming out. But having said all this.....I'm in no way saying I'm right! Just my theory....And I do like to hear others' ideas..
 

Gigitt

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I like to do my oil changes on a warmed up engine.... time is no issue... i let it drip for 30-60 minutes while i go other things.
But basically sump bolts tend to come undone easier when warmed up.
 
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