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TAN · 11-10-2021, 08:37 AM

About 50% of the time I change my oil with the motor cold. My reason for this is:When I drive it and then park it and check the oil in the morning it will be down about 1/2 a quart. If it sits for several days it will show that oil is where it should be.I feel that after it has sat for several day I get an extra 1/2 quart more oil out of it then I would if I warmed it up. I would appreciate any and all comments on this? Thank You

Mudfrog · 11-10-2021, 10:33 AM

In a way, what you're saying does kind of make sense because the half quart extra means more oil has drained down to the pan and you'd have a more complete drain. But, I don't think this is what you need to be doing.

Warming the oil up allows it to drain easier and also helps to carry out more impurities that are mixed in during the drain. Myself, since I change it regularly, I'm not concerned that there might be a little bit of old oil left in the engine.

wolfe10 · 11-10-2021, 10:38 AM

Quote:

Originally Posted by Mudfrog

In a way, what you're saying does kind of make sense because the half quart extra means more oil has drained down to the pan and you'd have a more complete drain. But, I don't think this is what you need to be doing.

Warming the oil up allows it to drain easier and also helps to carry out more impurities that are mixed in during the drain. Myself, since I change it regularly, I'm not concerned that there might be a little bit of old oil left in the engine.

Yup, hot only.

And, if you are concerned about the little bit of oil that is not in the pan, pour in 1/2 quart of new oil with the drain plug still out to "flush" out most of the remaining oil. Suspect you will find that 1/2 quart comes out clean/like new.

RightUR · 11-10-2021, 10:57 AM

IMHO you are overthinking it. We have all these filters and preventive measures/applications on our rigs, that I really don't think 1/2 quart is going to be detrimental or have much of an impact at all.

Soppy · 11-10-2021, 03:24 PM

For the best of both worlds you could drain it hot and leave the plug and filter off for a few days to let it all drip out.

CRV2 · 11-10-2021, 03:38 PM

Keep in mind that when you first start the engine after changing the oil that there is a brief period of time that the engine is running with little to no oil pressure. With that in mind, it is very important to have recently ran the engine prior to changing the oil (whenever possible) as that extra ~.5 quart you see overnight would in the more recent time be a good coating of oil on the cylinder walls and in all of the bearings and other engine components which is important to have the entire engine warm and well oiled when restarting after an oil change. ~CA

wolfe10 · 11-10-2021, 03:57 PM

Quote:

Originally Posted by Soppy

For the best of both worlds you could drain it hot and leave the plug and filter off for a few days to let it all drip out.

OK as long as you (REALLY IMPORTANT) isolate/cover both drain plug and filter housing to insure that no dirt can get in.

Me, I would not do that.

Drain hot. If still concerned, pour a 1/2 quart of new oil through.

Now, even the most anal of us should be comfortable.

We are likely going WAY overboard on this!

Full-Timers · 11-10-2021, 07:42 PM

Use to be draining your oil while warm was the right way to do it because it helps to remove sludge. With the detergents in new oils, that no longer holds true. If you have sludge in your engine you are not maintaining it properly. Also filling your oil filter is not a good idea because oil enters the filter from the outside of the filter element and exits into the engine from the center. Filling the center could introduce contaminates into the oil/engine. With the tight tolerances in todays engines the smallest bit of contaminate can cause problems. Oil pressure builds soon enough that completely draining the engine and not pre oiling the filter will not cause any problems whatsoever.

TAN · 11-11-2021, 04:39 PM

Well I warmed the motor up and changed the oil when it was hot.Thank you everyone.

George Schweikle · 11-17-2021, 06:28 AM

How can filling a new oil filter from a just opened new container of oil "introduce contaminants" into an engine?. Unless I am missing something, this just doesn't make sense

Quote:

Originally Posted by Full-Timers

... Also filling your oil filter is not a good idea because oil enters the filter from the outside of the filter element and exits into the engine from the center. Filling the center could introduce contaminates into the oil/engine.....

wolfe10 · 11-17-2021, 06:50 AM

Quote:

Originally Posted by George Schweikle

How can filling a new oil filter from a just opened new container of oil "introduce contaminants" into an engine?. Unless I am missing something, this just doesn't make sense

George,

We had a retired petroleum engineer at one of the Diesel RV Club Maintenance Seminars.

When the subject came up, he kind of laughed and explained that new oil in the container from the refinery SHOULD be clean, but occasionally particulates could be found in it. He strongly suggested either not filling the oil filter, or being extremely careful to only pour oil in the outer holes (inlets).

And, he said prefilling the oil filter was more about making the owner feel good than protecting the engine. The oil film on the wearing surfaces would protect the engine for way, way longer than it takes for the filter to fill and oil pressure to build.

Lastly, he said, "do what makes you feel good", all except filling the filter center hole/outlet.

MoCoTom · 11-17-2021, 08:18 AM

If starting with an empty filter is not detrimental to an engine why do filter manufacturers put drain-back valves in most of their products. Filters that are mounted horizontal or at any angle will allow some or most of the oil to drain out of them hence the drain-back feature was designed to stop this from happening. Sorry but I'm not following the reasoning behind the empty filter theory
Tom

wolfe10 · 11-17-2021, 08:29 AM

Quote:

Originally Posted by MoCoTom

If starting with an empty filter is not detrimental to an engine why do filter manufacturers put drain-back valves in most of their products. Filters that are mounted horizontal or at any angle will allow some or most of the oil to drain out of them hence the drain-back feature was designed to stop this from happening. Sorry but I'm not following the reasoning behind the empty filter theory
Tom

Tom,

Difficult for me to equate a "dry filter" once a year at oil change time with a dry filter hundreds/thousands of times the engine is started during the year.

But, please do what makes you comfortable. I have nothing to sell.

CRV2 · 11-17-2021, 08:45 AM

Quote:

Originally Posted by MoCoTom

If starting with an empty filter is not detrimental to an engine why do filter manufacturers put drain-back valves in most of their products. Filters that are mounted horizontal or at any angle will allow some or most of the oil to drain out of them hence the drain-back feature was designed to stop this from happening. Sorry but I'm not following the reasoning behind the empty filter theory
Tom

The reasoning is related to what I was saying in comment #6. When you run the engine and warm it up just prior to an oil change, all of the engine components gets well coated with oil and when you restart (hopefully within an hour of the engine running) the engine has lubrication that will help protect the engine until the filter fills and oil pressure returns.

On the other hand, without a drainback filter feature, on designs that would otherwise empty the filter of its oil, when the engine sits for a while, even overnight but more concerning is days, in any case a lot of the oil that was coating the engine components for the first hour after shutdown has now drained back into the oil pan (hence why the OP stated his oil level is a .5 qt higher after sitting overnight), and with that, a start of the engine after having not run recently results in an engine that has not been recently well lubricated and when starting the less lubricated engine, having oil pressure asap is very important to protect the engine (which is why the filter anti-drainback valve is important).

With that, I don't see any harm, only good when prefilling the filter cleanly and I would suggest to use something like a turkey marinater syringe or something similar to fill the filter from its outer holes (to prevent anything being unfiltered when restarting).

Many years back it was not uncommon for certain mfg's to recommend disconnecting the power to the electronic ignition just after an oil so the engine wouldn't start (more to protect the earlier turbos), and then to spin the engine starter over for 10~15 seconds to fill the filter and start pumping oil to the point you have oil pressure then reconnect the power to the electronic ignition and start the engine. I am not sure how easily that could occur though with newer engines as I don't know if they have a specific fuse or similar that would allow one to spin the engine over without starting, but perhaps there is and if so that wouldn't be a bad thing to do. I just warm up the engine, then drain and add the new oil and filter usually within 15~20 minutes of running and simply restart the engine afterwards, low idle for sure for the first minute or so. ~CA