Rauhbatz

My 126K mi 2007 ML350 has always been warmed up when the temps are below 40 degrees F. I let it warm up not all the way to 80C...but at least to get the temp needle off the step.

Piston engine aircraft require warmups to make sure they are at operating temps before the engine forces for takeoof. I used the same logic for cars.

Any thoughts on this welcome as its an ongoing family discussion.

BTW I also posted this query on the 190E board...response so far is do a warm up

iankayem

Aeroplanes need full power to get off the ground. Full power needs a warm motor with oil flowing freely to all parts.

Motor cars can be safely driven away at moderate speed after minimal warming (subject to ambients). Just enough warming to ensure the oil is flowing can be achieved in the time it takes to buckle your belt. Just make sure you don't take on a challenge at the nearby traffic lights, but let the motor warm as you drive.

In the snow, I do start the motor before scraping the windscreen clear (the heater helps this). Of course I do not try full power in the snow at anytime.

listerone

For years my rule of thumb had been let the car idle for a minute of so after starting in cold weather then drive off at reasonable revs for a while after.Automotive engineers,of course,could disagree but...

mhammady

I'm not an engineer, but I do warmup for 2-3 min prior to the morning trip, even at winter our temp is around 40 F

KA8

I never warm up my ML. I let it idle for about 15-20 seconds then go easy until it's fully warmed up.

Breitling65

Any engine will benefit from warm ups, that is because of oil can't lubricate as well on cold. Modern engine and oil however need this less time than before on non fuel injection types of engine. You could drive slower instead of warm up with same effect. I would say that warm up is important for automatic tranny as well.

Rauhbatz

Looks like with MLs that are more modern than my trusty 190E a modest warm up is OK....especially with the light oils (Mobil 1 ) that find their way into sump...

Cyber GS

Depends on temp. This morning it was 19 degrees so I let it warm up for at least 5 mins before driving. During warmer months its usually start and drive, but I do drive at slower speeds until engine temp increases.

jkaetz

Unless the ambient temp is consistently < 0º F, any warmup beyond 30 - 60 seconds is a waste of fuel on a modern engine unless you plan to immediately go racing upon putting it in drive. Your engine will also warm up much faster at normal speeds driving through your neighborhood than at idle. In addition, warming your engine at idle is doing nothing for the transmission and other gear oils which will also need to come up to operating temp before spirited driving.

LadyMeg

My Indy, who previously worked for MB and now only services MB vehicles, advises his customers to "don't bother warming up your car before driving--it's not necessary."

zemun1234

I think point of this is 'now only services MB vehicles'

I am doing warm up until RPM drop below 1000 - it could be 4-5 sec or around 15 sec during winter.

N_Jay

Start engine, put on seat belt drive gently for the first minute or so.

Idling for warm-up is no better then gentle driving for the engine and a waste of time and fuel as far as warming up the rest of the running gear.

As for very cold starts, as soon as the engine is running smooth you are ready to go. (Usually right away or 5 to 10 seconds at worst).

chikoo

totally agree with both of you.

I once worked in an office that was less than 1 mile away from I-90. There were couple of times that during winter after I leave work, I had to gun the engine to 5-6K to merge with traffic. I inevitably got the check engine light. So I took it to the dealership and they printed out what the computer had captured - which is I was racing the engine within 1 minute of start up. I learnt my lesson the hard way.

N_Jay

I don't think there is a "Racing the engine within 1 minute of start up" code.

Mechanics are good at excuses.

chikoo

<p>. This car was not a MB. I saw the computer readout myself. This car was a running quite an advanced version of computer for its time in 2003.</p>
it captures the engine runtime. Not an error code. The code was for a misfire.

davey one

The other thing to think of on the CDI MLs is to let the turbo cool down with a 15 second tick over if its been a fast run

mhammady

I do 1-2 min till engine sound calm down and RPM drops below 1000

ML350 2010

N_Jay

The idea of waiting for the idle to drop is a little bit backwards. It runs fast to keep it off idle till it is warm enough to idle at the lower speed and also to get it to the point where the FI system can rum in closed loop mode.
Driving gently does this faster and wastes less fuel, making less emissions than just idling it. (even at the elevated idle.)

dgiturbo

Per Mercedes manual, no warm up required. Per Mobil1 website, the 229.5 or .51 oils are ready to go down to -40C. (If you are below that well... I think you will be idling because you wont feel your hands to drive)

Start up, buckle up and your ready to go.
You can try to race at that point, but if the ECU doesn't see what it likes re temps etc., it will do what it needs to and retard the power output. It can also fully ignore your right foot request if needed. (Ever had a limp home issue?)
Sitting and idling for a 1970's style carburetor choke warm up on our ML's is a waste of fuel.

chikoo

the oil may be ready, but is the metal ready in that freezing cold?

u001elg

This is a loaded question... even though it appears simple.

To answer it correctly and fully, one would have to know the driving conditions immediately after starting your ML.

Do you go from a cold start and put the engine to high revs or load right after start (i.e. several posts above where there is a distance of less than a mile and hard acceleration). It that case then, yes, allowing the oil, coolant and engine in general to warm for a short time is helpful.

If you go from a cold start and gently drive in a rural or neighborhood setting then no, the engine will warm quicker with gentle driving.

To go to the extreme, my workplace has a set of eight 4500 HP diesels that must start and be fully loaded at max RPM within 10 seconds of a start signal. For this application, the coolant is constantly heated, as well as the oil and both are circulated. All oil lubricated components are kept at or near normal operating temperature and pressure all the time. I hope that you are not driving in this manner...

Some emergency vehicles (fire and rescue) are treated in a similar fashion with engine coolant/block heaters and oil heaters. Airplanes, especially piston powered craft, are required to be at temperature - this is for two reasons: 1) full engine load is generally required for takeoff and 2) on carbureted engines the availability of carb heat is extremely important to prevent icing and maintain mixture.

I doubt that few, if any, of us civilian drivers subject our vehicles to this kind of abuse on a regular basis. Therefore, I agree with the post that states as a general rule of thumb no daily warm up period is necessary and this will also cause the least amount of emissions discharged and fuel to be utilized.