Warming engine - under load

[goodoleboy]

There has been long debate over to let a engine warm for 30-60 seconds then driving away.
My question is does the engine work harder under load of of backing up and driving away?
If so, does the 30 second warm up benefit?

[ January 22, 2004, 08:23 AM: Message edited by: goodoleboy ]

 

[n8wvi]

I think it depends on the temp and the fluids used. If it's -40 and the vehicle wasn't plugged in, I think a stationary warm-up for at least a few seconds is in order! However, if it's freezing or above, I typically only idle long enough to put my seatbelt on, then gently drive away.
Dave

 

[TallPaul]

I think the main thing is you want to wait until the oil delivery system is pressurized. In warm weather it might be a couple seconds, but in cold weather it takes a bit longer. I started my truck in 10F weather it was nearly 3 seconds for the oil pressure needle to leave zero, then a few more seconds to get near full pressure. In warm weather my pressure goes up to about 53 psi in a few seconds, but in this 10F stuff it only reaches about 47 psi at first and then after I drive a half mile it's up to 53. The oil is pretty cold and thick. However, I don't usually idle longer than 5 to 15 seconds. Once the idle drops to normal you should be fine to drive it moderately until it comes to full operating temperature. Backing out the driveway is not a lot of work, though more than sitting at idle, unless you lug it.

 

[drm7]

I let my vehicles 'high idle' for 30-60 seconds until they kick down a little bit then I drive off. I then drive easy for the first 2-3 miles until it starts warming up. My truck idles around 1500 for 30-60 seconds then kicks down to around 1100 and once I start driving the idle drops down to normal. My Mazda MPV van will idle around 1500 and I don't know how long it would take to kick down. It seems that it would idle at that rpm for 5 minutes if I let it. I just try to wait until I have good oil pressure and circulation before driving.

 

[heyjay]

It depends on how quickly the motor has to work. I live 3 miles down a gravel sideroad with a maximum posted 35 MPH speed.

So once I back out of the garage, by the time I close the doors, I leave. It's only going 30-35 MPH. By the time I get to the highway, it's fully warmed up even at -40 F.

On the other hand, if I lived along the highway where after leaving the driveway I'd have to hit 55-60 MPH, I'd make sure the temp gauge was at least 180. To go from cold to full highway speed ASAP is murder on cold engines.

 

[batterycar]

I just drive it. The more fuel you dump into your engine, the faster it will heat up.

 

[TC]

One company's opinion (Shell)...
"Does it help to let your car warm up in winter before you start driving?"
"During the winter when an engine is cold and the oil is thick, DO NOT rev up the engine immediately after starting it. The best compromise is to wait two or three minutes, then drive slowly for the next five to 10 minutes until the engine reaches the proper operating temperature. This procedure keeps engine revs down and builds up the oil pressure required to allow lubricating oil to move throughout the engine. One of the main purposes of lubricants is to control friction and subsequent wear by putting an oil film between moving metal parts. Critical lubrication areas are the camshaft and connecting rod bearings, the cylinder walls and pistons. It takes a few minutes for the engine temperature to warm the oil to make this lubricating process work properly."
http://www.shell.ca/code/motoring/tips/engines.html

 

[heyjay]

That sounds like a bit of waffling on Shell's part. Since I have to drive down a 3 mile gravel sideroad with a posted 35 MPH, I'm probably the "ideal" candidate for this procedure.

Say the highway with a posted 55-65 MPH is at the end of your 100 ft long driveway. Do you spend 10 minutes at 35 MPH while taking the risk a sleepy morning commuter may rear-end you??

A little bit of common sense works wonders here! Though I have seen folks pull right in front then drive at 35-45 MPH for the next 10 minutes to baby their precious motor until it reaches operating temp: sure feel like engaging "ramming speed."

If I had to hit highway speeds within 200 yards of my house, you bet I'd make sure the thing had warmed up till the gauge read 180 F. Then I'd take off and reach highway speed, so you don't have 20 cars stuck behind you trying to impatiently pass on a 2-lane and cause a nice head-on.

The proper oil viscosity in cold weather ensures proper lubrication at start-up. In extreme cases you have to research MRV values to find the lowest possible at the given temp.

That's why I have to use Mobil 1 0W-30 in my GMC Vortec 5.3 in winter. Or the thing knocks and clatters.

Remember that most gasoline motors don't use continuous pressurized oil delivery, but depend on "splashing" to lube the piston pins and some of the camshaft lobes. Not much "splashing" going on with oil like taffy.

 

[Robbie Alexander]

What is LOAD?

I would say long enough to get all the oil flowing then hit the road, but not anything heavy.. take it easy until engine is warm, then feel how it responds, and when it acts normal, then HIT the PEDDLE to the metal

 

[Chevy Guy]

I remeber a study done some years ago by AAA stated its was generally a good practice in respect to fuel milage and general wear to start your car and let it run for 30 seconds to a minute and them drive at a moderate (not excessive) speed/load for the first 10 minutes. This allowed the oil to circulate well and the engine to warm up during the inital drive. I would say this is an excellent procedure for about 15-20 degrees F and above, any colder and I would let it idle for at least 3 minutes.

 

[Patman]

Instead of idling my car, I simply start it and put it in gear right away, but I do not touch the gas right away. It's automatic, so I just let the engine pull the car along without touching the gas for the first 30 seconds or so, while I pull out of my townhouse complex (I need to go over a speed bump anyways, so there is no need to be moving too quickly)

Then I drive through a small subdivision for a minute or two, giving it very light throttle so it's holding at around 1500rpm. By then, I have to pull onto a busy 50mph road, but usually am able to pull onto it and still keep the rpms below 2000. This is one of the nice things about having an LT1 350 which makes 325ft lbs of torque at 2400rpm (and probably 75% of that torque even at idle speeds), is that I don't need to give it a lot of throttle to keep up with traffic.

I truly believe that the gentler you drive your car during the initial few minutes after a cold start, the longer your engine will live. It's more critical in the winter, but it still helps in the summer (I do my same warmup procedure even when it's 90 degrees outside, since oil at 90 degrees is still going to be a lot thicker than oil at operating temperature)

 

[JohnnyO]

Way colder the past two weeks than even PA is supposed to be.
1. Start truck or van, depending.
2. Switch off OD.
3. Idle about 8 blocks mostly downhill to donut shop.
4. Park, leave engine running.
5. Get donut, coffee, read sports pages, more coffee, talk cars with my cousin and a mechanic guy that comes in, more coffee.

6. Walk briskly across icy parking lot to now-warm truck or van.
7. Drive to work.

 

[moribundman]

quote:

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4. Park, leave engine running.

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You're lucky to live in a place where your car is still waiting for you when you leave it alone for a few minutes.

 

[rugerman1]

quote:

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Originally posted by moribundman:

quote:

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4. Park, leave engine running.

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You're lucky to live in a place where your car is still waiting for you when you leave it alone for a few minutes.

---

If somone tries to steal Jon's truck,he'd just throw some De Angelis Donut Shop coffee on them.That stuff will melt Titanium!

Mark

 

[Starbreaker666]

Here in Limon Colorado my truck gets warmed up in the drive way for 10 minutes before it ever moves. Then I drive 3 miles to work at 65 mph. This is one of the reasons if change oil at 3k miles no matter what brand I use. I repeat this proccess 5 days a week...=)

 

[Santo Fontana]

I leave my car running at the coffe shop and lock it with my spare key.

quote:

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Originally posted by moribundman:

quote:

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4. Park, leave engine running.

---

You're lucky to live in a place where your car is still waiting for you when you leave it alone for a few minutes.

---

 

[JWRENCH]

I have to run mine a couple of minutes just to defog the windows where I can see where I'm going in the winter. I usually start it and let it idle 5-10 seconds then try to hold it around 1800 rpm's like you would do if you were starting up a rebuilt dry engine for the first time.

In the warmer months I just give it 10-15 seconds to pump the oil up to the top end and go.

 

[StiMan]

i let mine run for 5 to 10 minutes.

on my previos car, which i had since brand new, and sold it at 40,000kms whenever i did a cold start i could hear tappet sound. this only went away after the car fully warmed.

never knew what this was, but the car never missed a beat and had the noise since new and i had synthetic in there from 1000kms onwards.

 

[Bugzii]

My warm-up routine:

On cold starts, my car (like newer VWs) has a "secondary air injection pump" that blows additional air into the exhaust manifold while the engine is running rich. The extra fuel and air causes an after-burn below the exhaust manifold to heat up the Lambda probes (oxygen sensors) and the CAT converter. The engine idles at ~1200 rpm during this stage for about 45-90 seconds. I use this time to adjust mirrors, seat and secure the seatbelt.

Once the Lambda probes are warm, the Air Pump stops and idle will then drop to 800 rpm. Off I go, driving gently till the "blue" temp indicator goes out, which means that coolant is at normal operating temperature. This usually takes 1/2 mile. I don't load the engine till the oil is at normal operating temp.

[ January 23, 2004, 06:13 AM: Message edited by: Bugzii ]

 

[novadude]

quote:

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This is one of the nice things about having an LT1 350 which makes 325ft lbs of torque at 2400rpm (and probably 75% of that torque even at idle speeds), is that I don't need to give it a lot of throttle to keep up with traffic.

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Yup. Same with my 5.0 Mustang. With my AOD, shifts always happen below 3k rpm at light throttle, so I do not feel bad starting up the car and driving away. I figure the throttle opening and rpms are so low it won't hurt anything.

Mr. Dyson tells me that my oil analysis reports show that the engine is "well maintained and well driven", so I guess my warm up procedure works.