Warming up the engine before you drain the oil.

[jake1050]

Almost everytime I read this, the reason given is that warm oil will drain faster. I have a couple of problems with this and will offer my own opinion as to another reason why it might be a good idea to drain oil from a warm engine.
In actuallity a cold engine will drain more oil faster than an warm engine. Here is why. The last time you ran the engine it was plenty warm and 99% of the oil has had time to settle down into the lower oil pan area. Opening the plug will cause this oil to drain out. Then once the oil is empty you will be left with a very slow drip. This would probably take about 8 to 15 seconds to accomplish.
Removing the drain plug on a warm engine may drain the pan in 7 to 14 seconds but instead of a very slow drip you will get a slow trickle because of the oil that is still drifting down from the engine by gravity. You will be tempted to let it drain for a few more minutes. So there you are talking minutes from a warm engine and seconds from a cold engine.
I will be the first to admit that most of us are not in so much of a hurry to get back on the road that the oil drain time is going to bother us and much more time can be gained during the oil filter change.

I can, however, think of another reason to drain the oil from a warm engine. Running the engine gives the parts one last coat of oil before it is restarted on an empty oil filter and possibly empty oil pump. Thus providing some much appreciated lube while the engine is waiting for the new oil to make its way to the critical parts. I have no idea if those few seconds waiting for the new oil to flow is that detrimental but I definatly would not want to do that to a bike that has not been ran for a week or more.

[jake1050]

I had much better paragraph indents before I submitted that thread. So my appologies for them getting tossed.

[markjenn]

You make some good points. This is one of those things where you'd have to do some serious data collection to know which of the factors you mentioned is dominant.

My opinion is that it is not worth worrying about, either way. Most any engine typically has 10% of so of its capacity as undrainable; when you're leaving a 0.4 qt behind, does it matter whether it is 0.38 qt or 0.4 qt?

- Mark

[RIQUE]

I consider the warm oil thing pure B.S. It is my firm opinon that best drainage is accomplished by opening the drain plug and leave it overnight. Gravity will drain all the drainable oil. Make sure you remove the oil filter too, therer is oil from that end that will slowly pour. I did a couple of runs and always get more oil from letting it drain overnight.

[Samsons Revenge]

Originally Posted by jake1050

Almost everytime I read this, the reason given is that warm oil will drain faster. I have a couple of problems with this and will offer my own opinion as to another reason why it might be a good idea to drain oil from a warm engine.
In actuallity a cold engine will drain more oil faster than an warm engine. Here is why. The last time you ran the engine it was plenty warm and 99% of the oil has had time to settle down into the lower oil pan area. Opening the plug will cause this oil to drain out. Then once the oil is empty you will be left with a very slow drip. This would probably take about 8 to 15 seconds to accomplish.
Removing the drain plug on a warm engine may drain the pan in 7 to 14 seconds but instead of a very slow drip you will get a slow trickle because of the oil that is still drifting down from the engine by gravity. You will be tempted to let it drain for a few more minutes. So there you are talking minutes from a warm engine and seconds from a cold engine.
I will be the first to admit that most of us are not in so much of a hurry to get back on the road that the oil drain time is going to bother us and much more time can be gained during the oil filter change.

I can, however, think of another reason to drain the oil from a warm engine. Running the engine gives the parts one last coat of oil before it is restarted on an empty oil filter and possibly empty oil pump. Thus providing some much appreciated lube while the engine is waiting for the new oil to make its way to the critical parts. I have no idea if those few seconds waiting for the new oil to flow is that detrimental but I definatly would not want to do that to a bike that has not been ran for a week or more.

Interesting point 4 sure.

[Sal_R1]

How do you plan on getting the quart of oil out the cooler & its lines?

Originally Posted by jake1050

Almost everytime I read this, the reason given is that warm oil will drain faster. I have a couple of problems with this and will offer my own opinion as to another reason why it might be a good idea to drain oil from a warm engine.
In actuallity a cold engine will drain more oil faster than an warm engine. Here is why. The last time you ran the engine it was plenty warm and 99% of the oil has had time to settle down into the lower oil pan area. Opening the plug will cause this oil to drain out. Then once the oil is empty you will be left with a very slow drip. This would probably take about 8 to 15 seconds to accomplish.
Removing the drain plug on a warm engine may drain the pan in 7 to 14 seconds but instead of a very slow drip you will get a slow trickle because of the oil that is still drifting down from the engine by gravity. You will be tempted to let it drain for a few more minutes. So there you are talking minutes from a warm engine and seconds from a cold engine.
I will be the first to admit that most of us are not in so much of a hurry to get back on the road that the oil drain time is going to bother us and much more time can be gained during the oil filter change.

I can, however, think of another reason to drain the oil from a warm engine. Running the engine gives the parts one last coat of oil before it is restarted on an empty oil filter and possibly empty oil pump. Thus providing some much appreciated lube while the engine is waiting for the new oil to make its way to the critical parts. I have no idea if those few seconds waiting for the new oil to flow is that detrimental but I definatly would not want to do that to a bike that has not been ran for a week or more.

[jake1050]

Originally Posted by Sal_R1

How do you plan on getting the quart of oil out the cooler & its lines?

I don't know. How does the dealership do it? Will it not drain down with gravity?

[mechman]

Thought I would just mention a problem that can occur on draining the engine oil and leaving it to drain for a long period of time. What can happen is the oil pump can drain and get 'air locked', in this situation when the fresh oil is put back into the engine the oil pump WILL NOT prime itself and starve the lubrication system leaving no oil pressure. Serious engine damage can occur if the motor is run for a period of time. This can depend on oil pump location and it is paramount to replace fresh oil AS SOON AS POSSIBLE after an oil change. It is always recommended to get the engine to normal operating temperature before an oil change.
This has happened to me on several occasions with some BMW motor cars and my own Suzuki GSXR 1000. The cure is to fill the oil filter with oil and find a way to fill the main oil gallery with oil to try and prime the oil pump!!!!!!!!!

[john1000RR]

I have always thought the same way as the OP.

[mr. anderson]

one of the reasons you want to run your engine is to get any sediment on the oil pan off the bottom of the oil pan and have it suspended in the oil your are draining instead of sitting on the bottom of the oil pan.