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Spizzer's avatar
Spizzer
Explorer
Nov 28, 2017

A thought that goes against the norm!

All,

Thought I would post a thought I had that goes against what everybody does:

Conventional wisdom and recommendations say to change your oil after you have brought the engine up to temperature. The idea is that all the particulates that have settled in the pan get mixed up into the oil so that when it is drained you get a cleaner result. The problem with this is that the oil is dispersed throughout the engine in all the oil-ways and up in the rockers, etc. So theoretically, the most "complete" oil change is done after the engine has sat for an extended period of time giving all the oil a chance to make its way back into the pan. (I don't think I have ever changed oil and had the old oil stop dripping out the drain hole.)

Now, on to the sediment issue....a while back, after an unfortunate event, (a story for another time....) I had to drop the oil pan on my Cat C7. The rig had been sitting for weeks without being started. I drained the oil and dropped the pan. I was half expecting to find some thick sediment in the bottom of the pan, but to my surprise it was sparkling clean with just a thin layer of oil in it.

So, in light of this, it made me wonder if it is not better to do oil changes on cold engines? Running the engine just disperses the dirty oil of which some doesn't get drained.

What do you think? If you abuse your oil and don't change it regularly, then the sediment/crud issue could be a valid argument.

BTW, I have been doing all of my yearly maintenance and just changed the oil today. What did I do? Ran it around the neighborhood until it was hot and then changed the hot oil! Hard to stray from old habits.

I would be interested in hearing others thoughts on this.

Regards,

jeff
Class A
  • gutfelt's avatar
    gutfelt
    Explorer
    Nov 28, 2017
    ScottG wrote:
    gutfelt wrote:
    why would anyone want to get the engine hot and then try and drain hot oil and hot oil filter ?? answer no one so not sure where your coming from? second off why would u think you would have had sludge in your C7 oil pan?


    The vast majority of oil changes are done on warm engines - just as the manuals generally dictate.
    Personally, I've never found the oil to be so hot that it was a problem.
    Being hot, the oil drains quicker, more thoroughly and the filter is easier to get off as well.

    yes iam rather aware of oil and its draining techniques and have drained oil for over 50 years 35 of that as a mechanic
    I never suggested to drain your oil when its like 35 degrees
    but rather letting your oil sit for a few hours or even overnite in summer weather or in a heated building so its now drained down and still at a temp where its drains freely
    a oil filter neither comes off tougher or easier based on temperatures nor does as a poster opined does your oil become blacker over time quicker simply because you drained it cold verses warm that's not true; I prefer to let mine sit a few hours or over nite in the shop and then drain it cold no burns or hurt fingers that way
  • time2roll's avatar
    time2roll
    Nomad
    Nov 28, 2017
    I change oil when cold or maybe warm if it happens to be. I don't warm up the motor to change oil. Change on miles only, not time.
  • ScottG's avatar
    ScottG
    Nomad
    Nov 28, 2017
    gutfelt wrote:
    why would anyone want to get the engine hot and then try and drain hot oil and hot oil filter ?? answer no one so not sure where your coming from? second off why would u think you would have had sludge in your C7 oil pan?


    The vast majority of oil changes are done on warm engines - just as the manuals generally dictate.
    Personally, I've never found the oil to be so hot that it was a problem.
    Being hot, the oil drains quicker, more thoroughly and the filter is easier to get off as well.
  • MitchF150's avatar
    MitchF150
    Explorer III
    Nov 28, 2017
    I used to drain the oil cold, thinking the same thing as you..

    But, after doing it that way for several years with my old 86 Mustang GT 5.0, I found the dripping would take longer and longer with more of a stringy type of stream.. Not really a drip any longer..

    Also, I started to notice the oil would get "black" a lot sooner after the oil change too..

    Started warming up the engine first after that. I would warm it up, let it sit maybe 10 minutes, just so the exhaust pipes would cool down some and then let it flow..

    Not only did it flow out much faster, it flowed out smoother, and would drip again after a short time and never that stringy drip anymore.

    Started to notice the oil keeping it's color longer too..

    So, been warming up the engine first ever since than.

    Just my experience with it.. No idea if it makes ANY difference at all, but I feel better about it and since it's my vehicles, that's what I do.. :)

    Good luck!

    Mitch
  • gutfelt's avatar
    gutfelt
    Explorer
    Nov 28, 2017
    why would anyone want to get the engine hot and then try and drain hot oil and hot oil filter ?? answer no one so not sure where your coming from? second off why would u think you would have had sludge in your C7 oil pan?
  • ScottG's avatar
    ScottG
    Nomad
    Nov 28, 2017
    After warming up the eng, I let it sit for 10~30 minutes so it drains thoroughly.

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