Cold drain for 0w-X oils?

[ripcord]

Preferred oil change temperature is going to tend to correlate to where one falls on the BITOG OCD Spectrum <Trademarked>.

If a BITOG member uses HPL or Amsoil and top shelf filters, then the preference for doing scalding got oil changes is likely to be high. The preference for cooler changes will be greater for BITOG folk who use on sale oil and regular filters.

I'm in the second group. Idling for a few minutes is fine for me. As a 5k changer, I usually have multiple vehicles to do and don't want to take the time to mess around.



In case you were wondering, BITOG OCD Spectrum stands for "Bob Is The Oil Guy Oil Change Dependence"

 

[centertex]

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.

Not a dumb question. I think molecules of anything move closer together when cold and farther apart when hot. If you drain when engine and oil are hot movement should encounter less friction. I would drain when warm and compromise between burn danger and the desire to have as much oil drain as possible as easily as possible.

 

[Jackson_Slugger]

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.

I literally thought that was a given here. Maybe circumstances differ like the 3KOCI over a short period maybe it doesn't darken, but yes oil darkens for most over an OCI, but is a bit lighter when OPT hot over cold...

 

[supton]

I'll do it stone cold on even 5W30. Seriously, last weekend was the first time in nearly 10 years that I did a warm oil change, and that was only because the kid had to drive to my house. Stone cold 0W20 flows just fine, even in sub freezing temps, rolling around on the ground. I don't buy into hot oil holding that much more in suspension than cold oil--YMMV if your engine lacks an oil filter, or if you are changing a diff.

Haven't tried changing 0W16 at 0F but I'm guessing the oil would be the least of my concerns.

Anyhow, the further you are from -40C the more the oil is the viscosity of whatever the x is, reduced by any shearing and/or gas dilution.

 

[CR94]

I literally thought that was a given here. Maybe circumstances differ like the 3KOCI over a short period maybe it doesn't darken, but yes oil darkens for most over an OCI, but is a bit lighter when OPT hot over cold...

Of course engine oil darkens during use, but I don't see why you believe "hot oil is more translucent than cold." I'll guess that's an illusion resulting indirectly from the difference in oil's hot vs. cold viscosity (and to a lesser extent, in its mass density).