Cold drain for 0w-X oils?

[Elkins45]

I know this is a dumb question but help me understand. A multi-viscosity oil, say 0w-20 for the sake of discussion, is at 0 grade when cold and becomes 20 grade at operating temperature, correct? If so then why not do oil changes on a relatively cold engine as opposed to getting it up to full temp? Shouldn’t it drain just as well or better at 0 grade?

FWIW my anecdotal observation is that warm oil seems to drain faster, which is why I’m asking this dumb question.

 

[oil pan 4]

I say drain it as hot as you and your medical insurance can stand.

 

[oldhp]

My opinion is drain it as hot as you can stand it. The crud is in the oil suspension allowing more crud out of engine / oil pan. Now some people do it cold. But to me that allows some of the crud to stay in oil pan as it won't drain as well. The 0 grade really only applies how oil acts inside the engine. Just me.

 

[SubieRubyRoo]

I know this is a dumb question but help me understand. A multi-viscosity oil, say 0w-20 for the sake of discussion, is at 0 grade when cold and becomes 20 grade at operating temperature, correct? If so then why not do oil changes on a relatively cold engine as opposed to getting it up to full temp? Shouldn’t it drain just as well or better at 0 grade?

FWIW my anecdotal observation is that warm oil seems to drain faster, which is why I’m asking this dumb question.

Nothing wrong with cold drains. Just understand if you’re pulling a UOA the concentrations may be higher because everything is settled on bottom. At least that’s a best guess; haven’t pulled enough cold vs hot samples to say for certain.

 

[kschachn]

I know this is a dumb question but help me understand. A multi-viscosity oil, say 0w-20 for the sake of discussion, is at 0 grade when cold and becomes 20 grade at operating temperature, correct? If so then why not do oil changes on a relatively cold engine as opposed to getting it up to full temp? Shouldn’t it drain just as well or better at 0 grade?

FWIW my anecdotal observation is that warm oil seems to drain faster, which is why I’m asking this dumb question.

That’s not correct. It’s always a 20 grade oil. There is no such thing as zero grade oil.

All oils are thicker when cold and thinner when hot. They never go the other way.

 

[Rand]

I know this is a dumb question but help me understand. A multi-viscosity oil, say 0w-20 for the sake of discussion, is at 0 grade when cold and becomes 20 grade at operating temperature, correct? If so then why not do oil changes on a relatively cold engine as opposed to getting it up to full temp? Shouldn’t it drain just as well or better at 0 grade?

FWIW my anecdotal observation is that warm oil seems to drain faster, which is why I’m asking this dumb question.

its a 20 weight oil that passes the cold temp requirements for 0w rating.

m1 fuel economy 0w20 is 43.5cst at 40C 104f and 5x thinner at 212f.

(switching back to celcius)
so m1 0w20@40c is over twice as thick as m1 15w50 at 100c

All oils thin as they get hotter.. how much? That is what VI(viscosity index) describes.

 

[Jackson_Slugger]

I don't see the need to get any oil at over 200F, but just driving the car up ramps and letting it idle for a bit warms it up anyways regardless of grade. Hot oil is more translucent than cold when at the end of an OCI, so there are contaminants one wants out or at least I have a paranoia about it..

 

[CR94]

... Hot oil is more translucent than cold when at the end of an OCI, so there ...

?? That's a new one!

 

[Jackson_Slugger]

?? That's a new one!

You've never compared oil at op tamp to cold?

 

[Chris142]

A cold 0w is still much thicker than a hot 20 w

 

[eljefino]

So my prii run on 0w16 or 0w20. If I drain them hot the oil comes out so fast it splatters off the drain pan and makes a fine mist that makes a mess on my driveway. If I drain it cold or lukewarm it still comes out fast enough, I have no concerns about sludge being left behind, and it makes less of a mess.

The BITOG front page has good resources about oil viscosity. Think of its cSt (centistoke) viscosity as "absolute" viscosity, you can then find tables about how thick stuff really is at a particular temperature.

 

[Vitamin Yoda]

If so then why not do oil changes on a relatively cold engine as opposed to getting it up to full temp?

All my engines are very clean, so I don't do hot drains. What I do is park the car in the evening on my home made ramps with the engine hot. Then the next day I drain it. Everything is in the bottom of the engine at that point. It doesn't matter if it's a 5W-40 or 0W-20.

 

[KrisZ]

I used to do warm drains as the oil would come out fast enough. Basically I would idle the car for 5 minutes and that was hot enough.
However, ever since I installed the Fumoto drain valve, I need to drain when the oil is hot, otherwise it drains very slowly though that small opening.

 

[dumkid]

All my engines are very clean, so I don't do hot drains. What I do is park the car in the evening on my home made ramps with the engine hot. Then the next day I drain it. Everything is in the bottom of the engine at that point. It doesn't matter if it's a 5W-40 or 0W-20.

This is what I do too. I figure letting it cool off gives the oil time to flow out of the heads and galleys so I get more oil out. And it doesn't splatter. I doubt it really matters whether you do it hot or cold but cold burns less

 

[Eddie]

I warm my engine up by backing it up into the garage or ~4-5 minutes which is more than enough for modern synthetic oils. 0w20 drains like water anyway.

 

[Elkins45]

I had to move the car to drain it anyway so I decided I would just let it idle while I gathered my tools and supplies. It seemed to drain plenty fast enough.

 

[Hermann]

A cold 0w is still much thicker than a hot 20 w

My last two changes were done cold. 50°ish. Zero weight oil drains fast enough for me. Plus no hot engine parts to burn you. It is all right in the pan, and it comes out quite quickly. If I can get up on the ramps without the ICE starting up, it is done cold. Truck is still runnin'.

 

[Plawan]

I know this is a dumb question but help me understand. A multi-viscosity oil, say 0w-20 for the sake of discussion, is at 0 grade when cold and becomes 20 grade at operating temperature, correct? If so then why not do oil changes on a relatively cold engine as opposed to getting it up to full temp? Shouldn’t it drain just as well or better at 0 grade?

FWIW my anecdotal observation is that warm oil seems to drain faster, which is why I’m asking this dumb question.

Idle for 5 minutes and drain it seems ideal to me.

 

[CR94]

You've never compared oil at op tamp to cold?

Not in that sense. Please let us see your data showing the difference you're claiming in optical properties of used "oil at op tamp" vs. cold.

 

[Blueshound]

I did enough hot oil and filter changes when I fixed cars for a living. These days it's cold drain only. All the dirty oil is right down at the bottom of the engine already. And when it's cold it splashed around less. Win-win.