Does RPM matter when warming up a car?

We have a 1986 Honda Civic Wagon that is a true beater. I typically only drive it once a week because the motorcycle I ride isn’t really handy for transporting my gear to the bowling alley. At any rate, the car typically requires a good two-to-four minute warm up before it will idle without dying.

As I was warming it up this evening to go run an errand, I started thinking about the fact that I always naturally rev the engine at about 2800 RPM or thereabouts. But I realized I had no idea why I choose that particular spot on the tach. So what I’m wondering is, is there a particular RPM rate that:

  1. will warm up the car faster than other RPM rates; and,
  2. is best for the health of the car?

Keep it at the lowest RPM that it will run smoothly at, particularly if its very cold. Cold oil doesn’t circulate well. And under no load (i.e. idling) raising the RPM of an engine isn’t going to increase its heat output much at all.

Engine friction is often linearly dependent on engine rpm (assuming load, ambient temperature, etc. is a constant…don’t bust my chops here, I’m making a lot of assumptions). So higher engine rpm, all else equal, would warm the engine up faster. How much faster is open to debate, as engines vary in their engine friction. Japanese 4-cylinder engines typically have a low engine friction, whereas American V8s have a very high engine friction (exception would be newer ones…) However, there is a limit to this, as you want the engine to be somewhat warm before running it at really high speeds. Operating at 2800 rpm while sitting seems high and a bit unnecessary. It seems to me you really ought to see what’s going on with the choke on the car, so you can warm it up a better way, by light driving while it’s cold.

Could you explain that? ISTM that at higher RPMs several things will cause the engine to heat faster. More internal combustion and friction of all the moving parts specifically. You mention that the oil won’t be circulating well at first which would also make the engine heat faster (more friction).

If you want to get an engine to operating temperature without moving the car and without hurting the engine, 1600 RPM works nicely.
It’s what many modern cars idle at automatically, at first, in order to get the engine up to a temperature where they can begin enjoying the benefits of the catalytic converter.

I don’t warm up my car ever - I’ve heard that warming up is an “ago” thing, not done with fuel injection and other modern technology.

But I do wonder…If I lived in cold places that regularly had snow, would it be better on those -20C days to hold down the accelerator for a bit? Does it make a difference if you’re warming up from 10C or 0C or -40C? If the temperature is below freezing, does it make sense to raise the RPM to 2000 or 2500 or 3000 for a few minutes, or is it better to let the engine work its way out?

You say this last as though it were a good thing. Friction is not good. Friction causes your engine to wear out, and in extreme cases, seize up.

I’m guessing that the bulk of the engine heat comes from combustion, what with burning a nice blue flame in the top of the chamber and all.

I didn’t say it as if it were good or bad, I said it in rebuttle to Hail Ants’ statement that higher RPM doesn’t mean more heat.

Your car has a carburetor. It has an initial fast idle setting of 2500-3500 RPM, which would probably drop to 2200+/- when kicked off to the next step. I’d try to keep it closer to the 2000-2200 range if it will stay running there, as it entails less engine wear than running at 2800 for several minutes when cold.

This raises the question of why you have to keep it idling. Either the fast idle mechanism isn’t working, or it isn’t being engaged. If it doesn’t work, then your choice is to get it fixed or continue as you have been. But I’ve found that many people with carbureted cars don’t know the proper cold start procedure, so here goes:


Press the accelator pedal to the floor once and release it (two or three times if it’s bitterly cold). This does three things: 1) squirts a bit of gas for the engine to start on; 2) sets the automatice choke; 3) sets the fast idle mechanism.

Now, with foot OFF the gas, turn the key and start the engine. It should start and stay running at its fastest idle speed.

After a few seconds, “blip” the accelerator pedal - press down a bit and let right off. This will allow the fast idle to come down to its next step.

At this point, if all is in good order, the car can be driven (gently for the first few minutes). Alternatively, it can be left running to warm up. The fast idle setting will come down to curb (warm) idle speed over the next several minutes, in one or two more steps, but only actually drops to the next step when the accelerator is pressed. In other words, if you’re driving it or blip the pedal during that time the speed will drop, otherwise it will stay on fast idle until the pedal is blipped.