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Oil Changes, Hot vs. Cold


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7 hours ago, Grum said:

Have to be Hot........that thing would take 6 weeks to cool down! Can't wait to see the frame, wheels etc. arrive, gonna be an awesome bike.:laughing6-hehe:

A new Harley model . . .  the "Big Rod" .

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Few weeks ago I changed the oil in one of my motorcycles. Got a glass of tea, turned on the music in the garage, it was already on the center stand and proceeded to drain the cold oil from the bike. Once the oil was drained I placed a small shim under the right side leg of the center stand to allow for a full drain and went about my business. Was very nice not to have to heat up the engine and go that full route. I know this doesn't work for everyone because it's been so ingrained into us to heat the engine up before an oil drain, but for me I'm finished with that and I'm very comfortable with it. The comfort I feel is in the fact that I haven't pumped up a significant amount of contaminates up threw the engine to have them settle within the upper end. When I make plans to change the oil in one of my bikes, it's not as though I'm a part of a pit crew challenging myself to find out how fast I can drain the oil out of the engine. It's really all about taking my time and doing it the best way I can not the fastest way. For a lot of you this won't make any sense but for me it's very liberating to know that I really don't need to perform an oil change the way I've done it so many times before. I've learned a new way to perform a task now relegated to the past. Time to move forward.

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Well, consider the fact that there is a fair amount of oil sitting up around the valves and such. Draining cold means that all the contaminants

have settled out of the oil up there and will wait for the new fresh oil so they can continue to circulate. And possibly the oil in the pan has had

a chance for some of the gunk to settle to the floor of the oil pan and will sit there and not be flushed out. Nope, I'll stick to warm oil changes.

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Surely running the motor to heat the oil would also mobilise the contaminants and, once the engine stops, the free flowing oil will drain to the sump with the contaminants. The oil doesn’t need to be red hot to drain well. I run the motor to get the oil hot, but don’t crack the filter or drain plug until the exhaust has cooled enough to avoid 3rd degree burns!

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Although I'd say it really doesn't matter, and there's no way to get a full drain no matter what you do, I lean slightly towards warm but cold is perfectly fine too.  If you want "clean" oil, then you would simply change your oil every couple of weeks... I'd also say most I know change it more often than is necessary for engine longevity, but that argument is like asking what's the best oil to use.  I'd also say contaminants don't really settle that much, modern oils are designed to hold these in suspension more than the oils of the old days.  So, just do what makes you sleep at night is the only advice I could give.

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I always ran my old 6th gen. on the centerstand up to about 150 degrees F before draining the oil.  The bike had 101,000 miles on it when I sold it, and I think the engine was still running very strong.  Would it have made a difference if I'd changed the oil cold all those years?  I have no idea, but I can say I don't think there were any detrimental effects changing it the traditional way.

 

If I had changed it cold, I'd have saved a few slight burns on the back of my left hand from the header pipes while removing the oil filter!  :laugh:

 

By the way, I was always tempted to change the oil once with some cheap stuff and a cheap filter, run it for a few miles, then change it again with good oil and a proper filter, just to see how dirty the slightly used oil would be -- more like an oil flush than an oil change, to really clean out the system.  I'm sorry I never did get around to doing that.  Has anyone ever done this, and if so what were the results?

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I always run the bike for a minute

 

just to stir the oil up, but not up to running temp, a few high revs to get oil flowing, then drain it. This is just to pick up any contamination that may have settled out. 
 

Never drain oil from a hot engine, it acts as a heat soak for the main bearings. 

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On 8/10/2021 at 7:35 PM, Mohawk said:

Never drain oil from a hot engine, it acts as a heat soak for the main bearings.

Have not heard of this, or what the main bearings have to do with simply changing oil when hot. Are you saying you could somehow overheat the main bearings by draining the hot oil from around them?

 

Can you elaborate please?

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8 hours ago, Mohawk said:

 

Never drain oil from a hot engine, it acts as a heat soak for the main bearings. 

Negative... there is no objective reason to follow this advice...

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On 7/20/2021 at 12:07 PM, DannoXYZ said:

Major variable in article is NOT hot vs. warm vs. cold oil. It's drain-time!!! If they had left hot & warm oil to sit for 12-hrs, it too would've drained just as much, if not more!

I agree... short time you're draining the whole engine... long time
you're draining the pan... you get more of the old oil out with just
draining the pan because it takes time for the oil to migrate under
the force of gravity out of the whole engine and into the pan...

 

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You can't drain the "whole engine"........ 0.7 litres remain no matter how you do it, according to Honda.

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51 minutes ago, BusyLittleShop said:

I agree... short time you're draining the whole engine... long time
you're draining the pan... you get more of the old oil out with just
draining the pan because it takes time for the oil to migrate under
the force of gravity out of the whole engine and into the pan...

 

I prefer to let my bike sit and drain for a while when possible, maybe 30-60 minutes maximum.

 

BTW, I have to say we've taken the dreaded "oil thread" to a whole new level here!  :laugh:

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22 hours ago, BusyLittleShop said:

Negative... there is no objective reason to follow this advice...

Hi Larry, so how often do you run Mr RC45 for a good hard heat cycle then stop & drain the oil immediately? I'll start the guessing at never. 
 

Warm verses Hot ?  Hot oil drains immediately & hot shell bearings do not like losing their heat soak. Refill engine with new oil & at first crank you have no oil in the pump, so first few revs are with no oil pressure & very little residual oil if any. Why risk that ? 
 

Any way each to their own 👍 

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The oil drains out of the sump, this has nothing to do with the crank since the crank isn't submerged in oil. So draining the oil will have no

effect on "heat soak". The oil pump is going to be empty, whether drained hot or cold. No difference.

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On 8/11/2021 at 9:59 AM, Mohawk said:

Hi Larry, so how often do you run Mr RC45 for a good hard heat cycle then stop & drain the oil immediately?
 

 

 

Hiya Mo

I did stop and drain Mr.RC45 hot but will not any more after reading the article... I will long time drain the pan room temp...

RC45Grade30.JPG

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Interesting read - thanks.

 

Even though I've done countless oil changes in cars and bikes - I always hate watching the oil light stay on for those few seconds that always seems like an age whilst the engine circulates oil and fills the filter - worrying how much wear is occurring.

 

Those few millimetres that you don't get out on a warm/hot oil change aren't in the sump because they're still coating the bearings and moving surfaces for those few seconds of the post oil change startup - that's a good thing surely ? 

 

I'll be sticking with warm oil changes.

 

 

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On 8/9/2021 at 3:21 PM, TimC said:

By the way, I was always tempted to change the oil once with some cheap stuff and a cheap filter, run it for a few miles, then change it again with good oil and a proper filter, just to see how dirty the slightly used oil would be -- more like an oil flush than an oil change, to really clean out the system.  I'm sorry I never did get around to doing that.  Has anyone ever done this, and if so what were the results?

 

Not intentionally - but my bike has only done a couple of hundred miles in the last year due to Lockdown (like many of ours' I imagine).

 

Changed oil and filter last week at the 1 year point as usual anyway - oil came out surprisingly dirty, so perhaps a flush with cheap oil every few oil changes is worthwhile.

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I get the bike gudenhot (technical term). I park it and loosen the left side fairing or take it off (whichever mood I'm in), which takes a few minutes. I pull the plug and then go do other stuff.  Once the headers have cooled enough not to turn my hands into molten lava, I throw some aluminum foil over them to keep oil off and pull off the filter.  I then go do more stuff for at least a couple hours total if not more.  When I finally run out of stuff to do (not the honey-do list cause it never ends) I finally button everything up and fill it.  I get the benefit of hot drain (max particulate and moisture removed like the engineers want) and cold drain (max oil removed), plus I've got other really important stuff done like watching a ball game or a MotoGP race, cleaning the kitchen (by eating stuff), etc.  

 

The crank sits above the oil and the oil that lubes it starts draining into the pan as soon as you cut the engine off with or without an oil change.  The same heat soak process will occur whether the pan is drained or not.  If the crank was actually in the oil, there would be foaming (a bad thing), which is why you should never overfill an engine with oil. 

 

Slightly funny side note:  Our quint (ladder truck with a pump, hose, etc) was overfilled when I came on shift one morning.  I took it out of service until it could be remedied.  We found out that they used "trustees" (prisoners) to change the oil instead of doing it themselves.  They never removed the old oil before adding the new.  It was overfilled by gallons!  

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On 8/19/2021 at 6:00 AM, BlackheathMatt said:

Interesting read - thanks.

 

Even though I've done countless oil changes in cars and bikes - I always hate watching the oil light stay on for those few seconds that always seems like an age whilst the engine circulates oil and fills the filter - worrying how much wear is occurring.

 

Those few millimetres that you don't get out on a warm/hot oil change aren't in the sump because they're still coating the bearings and moving surfaces for those few seconds of the post oil change startup - that's a good thing surely ? 

 

I'll be sticking with warm oil changes.

 

 

Nothing to worry about.

 

I crashed my VF500F early-on once and cracked clutch-cover. All oil spilled out. Being stupid teenager, I didn't know what oil-light meant and I just ignored it. Drove it 30-minutes back to my parents' house. My dad scolded me and said I probably toasted my engine and he'd help be take it apart to repair. Once we got cases separated, measured main & rod-bearings and found they were all within spec with no wear!!!. That was 35-yrs ago and that same engine is running fine in my bike today! Bottom-end anyway...

 

Another data-point are original VFR750F & VFR700F bikes used to set world-record when they 1st came out. Honda wanted engines destroyed so they would never ever get into wrong hands. They were put on dyno with oil drained from engine and ran WOT throttle. Those engines lasted over 2-hrs before they died.

 

There are many engines and parts that use static oil-pool or splash unpressurised oil for lubrication. So... given zero load on start-up and low-RPMs, you don't have to worry about that short time while oil-pressure is building. Due to tight clearances, bearings are always full of oil no matter how hot or how long you wait to drain.

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21 minutes ago, DannoXYZ said:

Nothing to worry about.

 

I crashed my VF500F early-on once and cracked clutch-cover. All oil spilled out. Being stupid teenager, I didn't know what oil-light meant and I just ignored it. Drove it 30-minutes back to my parents' house. My dad scolded me and said I probably toasted my engine and he'd help be take it apart to repair. Once we got cases separated, measured main & rod-bearings and found they were all within spec with no wear!!!. That was 35-yrs ago and that same engine is running fine in my bike today! Bottom-end anyway...

 

 

 

Wouldn't you just put some oil in after replacing the cover and see how it sounded and ran first?

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I didn't know anything and my dad's not a bike guy. He was 1000% sure engine was goner. At least I got free set of manuals and lesson out of this! 🙂

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On 8/19/2021 at 6:00 AM, BlackheathMatt said:

I always hate watching the oil light stay on for those few seconds that always seems like an age whilst the engine circulates oil and fills the filter - worrying how much wear is occurring.

 

 

We should all be concerned because mechanics and manufactures agree... roughly 60% of total engine wear occurs during cold start up conditions before oil can

circulate through the engine... best to turn the engine over waiting on the light before combustion...

 

 Liquimoly Flow Test...  5w30 flows quicker than 10w40 or 15w40... so when choosing grades its best to pick a 5w30 over a 10w40...
 

 

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On 8/19/2021 at 3:00 PM, BlackheathMatt said:

Those few millimetres that you don't get out on a warm/hot oil change aren't in the sump because they're still coating the bearings and moving surfaces for those few seconds of the post oil change startup - that's a good thing surely ?

So it takes you two cold starts to do an oil change?

That's why I have never done hot oil changes: a lot of wear occurs during cold starts.

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1 hour ago, BusyLittleShop said:

We should all be concerned because mechanics and manufactures agree... roughly 60% of total engine wear occurs during cold start up conditions before oil can

circulate through the engine... best to turn the engine over waiting on the light before combustion...

 

 Liquimoly Flow Test...  5w30 flows quicker than 10w40 or 15w40... so when choosing grades its best to pick a 5w30 over a 10w40..

 

Depends upon how you use your engine. On every single engine I've worn out, it's been rings and valves that go 1st.

 

I would be interested in learning algorithm that arrives at that 60% figure.

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"I would be interested in learning algorithm that arrives at that 60% figure."

 

Yeah, me too. Wonder if it comes from that area near their back pocket? 🙂

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