What drains better?

[Geep]

Oil in the engine... hot or one that has sat for a month or more?

 

[Gwolf]

Warm oil would not be as thick as cold oil. That is not really the point. The point is to run the engine a while to stir all the particles that have settled in the low spots up in the oil so they will drain out when you pull the plug.

 

[pegasus1300]

warm to hot

 

[BajaRon]

Gwolf is right. Heavy, nasty stuff tends to settle out at the bottom. Not just the crank case. But everywhere. Including the cam lobe sumps and any depression in the system. You want to get that stuff up and suspended. Because there are a number of places where the oil will never drain from.

Hot oil flows best and will carry more bad stuff out than warm oil. I would never do a service on a cold engine if I could help it. But think about this. How often to you think the dealership gets the oil hot before doing a service?

Of course, you have to take some care with hot oil. But it can easily be done.

Typically, an owner will do a better job than a tech on many service items.

 

[Little Blue]

Hot Oil

....:agree:....DIY ....Hot is the best way. Remember to be Safe....:thumbup:

 

[2dogs]

Hot oil moves faster and splashes further. Sometimes you can beat cold oil to the spill point. But, warm oil is probably the best to work with.

 

[BajaRon]

Hot oil moves faster and splashes further. Sometimes you can beat cold oil to the spill point. But, warm oil is probably the best to work with.

Changing oil is like everything else in life. There are options. And each is a trade off. Once you decide what is most important to you. The rest is easy.

Keep in mind that for the WARM option to be effective. You must first bring your oil to operating temperature. Coolant operating temperature means nothing and does not guarantee that your oil is HOT (usually over 200 degrees). If you do not get your oil HOT, the end results with a WARM oil service will be greatly diminished. The whole idea is to get the contaminates suspended in the oil and change it before they have time to settle out and remain in your engine, transmission, crankcase, oil reservoir, nooks & crannies, etc.

1- Cold oil and cold engine parts are the safest and easiest to deal with. You don't really have to be very careful with it, and it doesn't splash much, if at all. DOWNSIDES - Drains slowly and leaves a great deal of contaminants just waiting to degrade your brand new oil! - This is the LEAST effective way to do an oil service.

2- Warm Oil and cooler engine parts are safer, with a low possibility of burns. It will splash more than Cold oil. But not as much as Hot oil. Also drains a good deal faster than Cold oil, but not as fast as Hot. This is definitely a BETTER way to do an oil service. DOWNSIDES - It will usually remove the lighter contaminants and a fair amount of medium contaminants. But heavy particles which settle out more quickly will probably remain behind. This all depends on how long the oil has been sitting after being hot to begin with. The longer it sits, the less effective your oil service will be.

3- Hot oil will suspended all but the heavy chunks (which you should not have to begin with). It drains faster (higher velocity) which tends to carry even the heavier contaminants out with it. It will give you the most effective oil service. So if this is your priority, it is the BEST way to go. DOWNSIDES - Hot oil and hot engine parts can be dangerous! You have to take some care when handling it. Because it is thinner, it tends to splash. It is also harder to get a mid-stream sample for oil analysis. Though getting an analysis on anything but a HOT OIL CHANGE is not going to give you accurate data because you are not capturing a representative contaminate sample.

There is a 4th option. Have someone else do the work. Dealerships usually do a cold oil service. Just something to consider.

 

[2dogs]

I opt mostly for the warm oil change and hope my/your filter catches all that it should.