Car question. Mostly idle (heh) curiosity.

[Girard442]

After many years I finally ditched my ancient carbureted vehicle and bought a used Subaru. The Subaru runs like a top even when stone cold, but I wonder sometimes if there's a long-term benefit to letting it warm up for a couple of minutes, especially on really frigid (10 ° F) days like today. Any thoughts?

Thanks,
G

[JT45242]

1. It's more comfortable for the passengers and let's oil lubricate

I remember click and clack talking about how oil settles when a car sits not running. Then the oil pump moved the oil when the car is started. Idling they said put less stress on the engine before it was fully lubricated.

Not sure with the new synthetic oils with extra additives if this is still truly needed. But I know remote starting my car and letting it warm up for a couple of minutes means that the car is warmer when I get in. Not just my butt from the seat warmer.

[bucolic_frolic]

2. I've always read to let it idle, particularly in cold weather

Lubricate the pistons, warms up the oil to let it circulate, reduces any metal-on-metal friction.

[MiHale]

3. It's good to warm up the oil as mentioned...

I was warned by a mechanic once that idling the engine does nothing for the transmission, so at first on really frigid days start slowly…no jack rabbit starts.

[MichMan]

4. Just start it up and drive

No high RPM until oil and water temperatures are at normal operating levels

[justaprogressive]

5. 30 seconds even at 0 degrees F

The multi-temp and or/synthetic oil doesn't need multiple minutes.

Not like the 30-weight of old!

No, warm it up for yourself (in the North we have remote starters
installed for exactly this purpose), the engine doesn't need it.

But take it easy on your tranny!

[ProfessorGAC]

6. I Agree With MichMan Above

A quick run to the store requires no real idling time.
Getting to 3k rpm merging onto the interstate, a different story.
Motor oils, since the early 80s are 70% refined oils & 30% surfactant. (Detergent) These are calcium neutralized to provide a way to greatly reduce acidity due to oxidation.
The surfactant also imparts a property called thixotropy to the blend.
What this means is that the viscosity drops quickly to the target due to the shear forces of flow, virtually irrespective of temperature. Plus, the shear rate in the cylinders is VERY high.
So, the oil gets to the ideal viscosity where it's needed most even if very cold.
It will rethicken in the oil pan, but since it's picked up heat in the cylinder the viscosity moves toward an equilibrium whether under shear or at rest.
By the time the temperature gauge on the car hits normal, the oil has been at phase equilibrium for probably 5 minutes.
The only reason I ever let me car warm up is to get the heat going to defrost the windows.