Oil changes: Warm or Cold?

[CobyRupert]

Does it matter if oil changes are down with a warm or cold engine?

Not sure if this has been debated here on TBN. There seems to be a wide debate on the internet.
I know the difference is miniscule in the big picture, and this is mostly an academic debate, but let's argue anyways.....

For 30 plus years, I've always warmed the engine prior to changing oil, mostly because I'm in a hurry.

My tractor is due for an oil change, and I just don't feel like (cold) starting it up for 10-15 minutes unnecessarily. (I'll probably compromise and plug in the block heater prior to draining, or just wait until after next time I use it). Assume in both cases, that one let's the oil pan drain for a >1/2 hour.

Cold:
Pros: Don't have to do one (1) unnecessary cold start.
More oil gets drained. Most of it ran down when oil was warm from the last time I ran tractor (Same as a hot oil change). However one would think that additional oil that has the extra time to run down to sump also gets drained.
Con: Particulate (metal shavings) that are setting on bottom of oil pan may not get drained because they aren't re-suspended in the oil like a recently run engine. But shouldn't they be in filter anyways?

What are other pro/cons to each method?

 

[tcreeley]

Warm engines drain faster, and carry any gunk with them more easily. They also drain more thoroughly.

But if you do regular oil changes with new filters, I don't think it matters. If I am changing the oil and its 15F - then I warm the engine so that the engine oil will flow more easily.- This is more important the thicker your oil is.

 

[Agvg]

Do you get the oil temp high enough if you run it for 10 - 15 minutes? And engines are made for cold starts, see a lot seems to think this is an issue but I can't quite understand the problem, the extra wear are more or less just a academic debate and not an real problem.

 

[Industrial Toys]

I would opt for warm, but then some oil is still on many surfaces, and will eventually run down. So maybe warm, but wait an hour after shutdown.

 

[deserteagle71]

I NEVER change the oil in any of my vehicles unless the engine has been run for a good long while and everything is hot. I want all the crap that may have settled out of the oil thoroughly suspended in the hot oil and drained out of the engine.

 

[Industrial Toys]

I'd like to be able to open a spigot when someone is tailgating me.

 

[dalola]

I NEVER change the oil in any of my vehicles unless the engine has been run for a good long while and everything is hot. I want all the crap that may have settled out of the oil thoroughly suspended in the hot oil and drained out of the engine.

Totally agree...... Not cold, not warm, HOT! Otherwise, you're leaving more stuff behind.

 

[jaxs]

The best way is the one that make's you feel best.:confused3:

 

[Jstpssng]

I'd like to be able to open a spigot when someone is tailgating me.

Preferably not with oil currently in your crankcase.
I watched an old 1954 movie about moonshine runners where the hero did that to a couple of thugs who were chasing him. He had a tank in the back and a valve that released the oil, much like the tar trucks you see on paving jobs.

 

[oosik]

I think Jaxs has hit the nail directly on the head. " Do it which ever way makes you feel best". Man - its a SLOW day at the fish market!!!!

 

[oosik]

I don't know why but this thread reminds me of a funny story. It was 1968 - we were in Palmer, AK - heading to our cabin for a week end. As we pulled into Palmer - there was a line of vehicles waiting for something. The highway from Palmer to Wasilla was being resurfaced. There was a Q waiting to be guided around the resurfacing job. It's our turn - we are half way around the resurfacing job - all of a sudden we hear the wail of a police siren. Check the rear view mirror - here comes the Alaska State Police - right up the lane that just received the hot top coat. He goes by us - him in the gooey lane - crap flying everywhere - up ahead he starts to pull back into the unpaved lane and all H*** breaks loose.

The hot top coat + chips has wound up on his tires like a black jelly roll. He is ALL OVER the road and finally ends up in the ditch - totally embarrassed but no injuries. Of course - in a small town like Palmer - it makes the weekly local newspaper - front page. The Anchorage newspaper picks the story up and runs it on page two.

The word is that whatever the contractor laid down never really hardened and they had to scoop up almost a mile and a half of this crap out of one lane. They waited eight days and finally decided to scoop it up because it was still soft, sticky and rolled up very nicely on vehicle tires.

 

[Wood_Butcher_Dav]

Would the oil flow better cold with multi-viscosity oil that are in most engines? As the oil heats it becomes thicker. Don't think it it really matters.

Dave

 

[Deere Dude]

Would dumping a couple quarts of diesel into the crankcase work for diluting the oil so it runs out faster and carries more gunk with it? It shouldn't hurt anything.

The reason I ask is I had a fuel pump leak in my truck and over a few thousand miles had about 7 extra quarts of oil/diesel in the crankcase. Never suspecting anything amiss, I pulled the plug and I had a gusher and luckily I had the capacity in my oil pans. The pump guy didn't seem to concerned. It cleaned out lots of gunk that day.

 

[Oldoak]

I NEVER change the oil in any of my vehicles unless the engine has been run for a good long while and everything is hot. I want all the crap that may have settled out of the oil thoroughly suspended in the hot oil and drained out of the engine.

Totally agree...... Not cold, not warm, HOT! Otherwise, you're leaving more stuff behind.

:thumbsup:

Just the way I have always changed the oil in any engine that I have ever owned. Hot!

I have also learned it is easier to loosen a spin-on oil filter while it is still hot or at least very warm. But don't loosen it to a point where it is going to leak while it is still too hot to handle. Then just wait for it to cool down and remove without being burnt with hot oil dripping on your hands.

 

[Diggin It]

Since I'm not too partial to bathing in hot oil, I'll go with the notion of letting it sit for a while after running, but not get too cool.

The quick change places are set up for hot engines, my yard isn't.

.

 

[Snobdds]

It was ingrained in me since I was a kid...

Change it hot and change it alot and an engine will never fail you.

 

[Oldoak]

The best way is the one that make's you feel best.:confused3:

That would apply to many topics here on TBN.

 

[MHarryE]

When the engine is shut down the hot oil is going to drain into the sump so if you drain it cold it doesn’t need to drain off engine parts except the oil pump inlet. If drained hot almost all the oil will drain off the parts. Worst is slightly warmed and then drained because gunk can stick to the engine parts. But with today’s oils it probably doesn’t make much difference. I remember the old days when the oil we drained started coming out in globs near the end, and that was with 1,000 or 2,000 mile changes on cars and pickups, 50 hour on tractors.

 

[dougtrr2]

Hot, otherwise you miss the fun of burning yourself on exhaust pipes and scalding yourself with hot oil.

Doug in SW IA

 

[mcfarmall]

I run the engine under full load until operating temperature is reached. Then I shut the engine down and monitor the temperature of the oil in the pan with an RTD probe until the temperature is at 135 degrees F and then pull the plug. This method allows for the maximum suspension of particulates while preventing contact burns from hot oil as it is below 140 degrees at the time of draining.