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Engine Warm-up time

23K views 95 replies 37 participants last post by  alcofribas 
#1 ·
This is my first bimmer and I'm not too familiar with it. My previous Hondas and Toyotas usually took a mile or so to reach normal engine operating temp. or the needle said so anyway. The 335i on the other hand takes at least 3 miles or something for the needle budge any at all. Is this true with your bimmers too? Caveat: I have not changed my route to work.
 
#2 ·
Your previous Hondas and Toyotas, and most non-performance cars, have a coolant temperature gauge. This warms up significantly faster than the motor oil temperature, which is what is displayed in your 335i.
 
#14 ·
This warms up significantly faster than the motor oil temperature, which is what is displayed in your 335i.
Oil temp really? Are you sure? Its strange that a mfgr would show oil temperature and at the same time not show water temp. Unless it is related to the turbos
 
#3 ·
The manual for my X3 says specifically not to idle to let the motor warm up. What's the reasoning?
 
#4 ·
Idling is not the most efficient way to warm up the engine. Nor is it environment-friendly. The best way is to get going applying light load, i.e. no flooring until the engine reaches its nominal temperature.
 
#5 ·
The above posts are true, but since the OP states it takes 3mi for the oil temp to budge, we can assume that he/she is driving said vehicle.

I suggest giving the motor 10-15secs on a cold start to settle down, but I would not exceed 40s of just "sitting" because it puts a load on the catalytic converter and is otherwise harmful.
 
#8 ·
The warm up time will depend on ambient temperature. When it is cold out it will take longer. It will also depend on how long it has been since youve driven your car. I believe that BMW states that you should not apply full throttle until at least 170F(?) or so. Coolant temp is not a good indicator of engine warmup, so I doubt your hondas were really warmed up. the 335i has a oil temp gage and this is the safe way to interpret warmup. I am a little more conservative and will not redline my car until 200F is reached.
 
#11 ·
the warm up time will depend on ambient temperature. When it is cold out it will take longer. It will also depend on how long it has been since youve driven your car. I believe that bmw states that you should not apply full throttle until at least 170f(?) or so. Coolant temp is not a good indicator of engine warmup, so i doubt your hondas were really warmed up. The 335i has a oil temp gage and this is the safe way to interpret warmup. I am a little more conservative and will not redline my car until 200f is reached.
+1
 
#9 ·
Here is my protocol: Start the car and let the engine run with the car parked until the engine idle drops down to the 800 rpm territory. Then drive slowly for about 1 - 2 miles. After the 1 - 2 mile point, normal driving. The initial high revs are programmed in to get the catalyst up to operating temperature as quickly as practical; so I let the catalyst get happy and then driving slowly for the 1 - 2 miles gets the rest of the engine 'warmed up'.
 
#67 ·
That's my routine. I have the advantage that my house is 1.5 miles from the freeway, so by the time I need to gun it, I can. :drive:
 
#13 · (Edited)
There are block heaters and oil heaters and blanket heaters to put your battery on. They are generic. They are generally 110V.

For the block you knock out a water jacket plug and insert a heating coil into the water jacket. Oil heaters are a straight heating element and go in via the dip stick tube.

There are many kinds. I used two in a car I had when I lived in Alaska. They worked great.
 
#19 ·
the most critical apsect of warmup is the oil temp. this is because oil viscosity changes with oil temp. When the oil is cool, it does not lubricate your engine properly(its too thick), especially if you run it hard. BMW's use of the oil temp guidelines will help your car last longer by preventing you from running your engine hard under substandard lubrication conditions. With an engine that has such close tolerances(any finely engineered powerplant), the oil must come up to a sufficient temperature so it is not too thick to lubricate properly. Kudos to BMW for using a better way to help you take care of your car. If you ignore their recommendations, the risk is higher engine wear and shorter engine life. If you live in temps near freezing, it can take 20 mins or more to warm up your engine to the optimal operating temperature needed to run it hard if left out overnight.
 
#20 ·
All of that palaver might be true if it were actually "oil" we were talking about, but BMW engines are not lubricated with "oil". The lubricant is not especially viscous when cold. Moreover, cold engine parts are smaller than warm ones. As a result, there's no special thing about low operating temperatures that would inhibit lubrication of engine parts, and the engine will accept normal operating loads when cold without damage. The oil temperature gauge does not help with this because its cold peg is at 160 degrees -- the internal temperature of well-done meat. If the gauge serves any useful purpose, it is to flag high operating temperatures, which are detrimental to both the lubricant and the metal engine parts.
 
#27 ·
It just kills me when on cold mornings, Sub 20 or so, I see people pull out of neighborhoods, etc. and just FLOOR it when I know the car has been running less than a minute. That poor engine........... :tsk:
 
#28 ·
I hate to see that too.

But as long as the engine had enuf time to build pressure at all points the damage will not be as great as driving immediately before oil has gotten to all.
 
#30 ·
Yes.

Oil leaks thru the valve guides and by the rings, especially if not broken in right or revved too early or if the oil changes have been too far apart
 
#37 ·
+1 Desertdriver

The entire argument of conventional vs synthetic oils really cracks me up. As desertdriver pointed out, they are both hydrocarbon based lubricants.... But what you're missing is this: without DynoOil there is no "AmsOil".... Synthetic oil is simply a "more perfect" derivative of what would be created by standard refinement. Synthetic oil is the AHHHHNALD of conventional oil.
 
#42 ·
The entire argument of conventional vs synthetic oils really cracks me up. As desertdriver pointed out, they are both hydrocarbon based lubricants.... But what you're missing is this: without DynoOil there is no "AmsOil".... Synthetic oil is simply a "more perfect" derivative of what would be created by standard refinement. Synthetic oil is the AHHHHNALD of conventional oil.
Some people dont know that crude oil contains MANY components, like thousands different molecules. Motor oil(dino) just is basically a boiling fraction of the crude. Aliphatics, olefins, aromatics, yes even esters exist in crudes. Synthetics are better controlled in the chain length and functional group variations, so they behave more consistently with a range of temps, but this doesn not mean they dont have a temperature dependence or viscosity index.
 
#43 · (Edited)
I've read that synth is superior in cold starts to dino oil because it will cling to the part for 5or 6 days where the dino is 2 to 3 days max, same conditions.

The main and rod bearings in your engine are lubricated by a process called a hydrodynamic wedge. W/o going into the details this process drags the oil with the rotating component and raises the pressure to 8 to 10,000 psi in the bearing preventing metal to metal contact.

So when you motor is running the crank and the rods are supported by the wedge (that can be around 0.0008 thick) so no metal to metal contact occurs, even under the pressure of a cylinder firing.

But when the engine is cold and started there is bearing material to crank main and rod journals surfaces. There is metal to metal contact until the hydro-wedge is established. And that takes time for the oil to get to the bearings in sufficient quantity. So the better the oil clings the better it lubricates. This is why you should give your engine a minute to get the oil circulated before you put a load the 'dry' bearings.
 
#44 ·
I've read that synth is superior in cold starts to dino oil because it will cling to the part for 5or 6 days where the dino is 2 to 3 days max, same conditions.

The main and rod bearings in your engine are lubricated by a process called a hydrodynamic wedge. W/o going into the details this process drags the oil with the rotating component and raises the pressure to 8 to 10,000 psi in the bearing preventing metal to metal contact.

So when you motor is running the crank and the rods are supported by the wedge so no metal to metal contact occurs, even under the pressure of a cylinder firing.

But when the engine is cold and started there is bearing material to crank main and rod journals surfaces. There is metal to metal contact until the hydro-wedge is established. And that takes time for the oil to get to the bearings in sufficient quantity. So the better the oil clings the better it lubricates. This is why you should give your engine a minute to get the oil circulated before you put a load the 'dry' bearings.
the clinging of synthetic oil to metal surfaces is purported to be due to the polarity of ester functional group/and metal parts. the PAO's(mobil one and many others) are not polar, hence the explanation doesnt work there. my problem is that I want to see hard evidence that significant amounts cling to the parts, enough to provide a film. Molecualr polarity and the adhesion energies involved are quite low. Im not saying that some tiny amount might not cling, but to say it is sufficient to provide the necessary film thickness to prevent metal to metal contact is a claim that is made only by the manufacturers, and they have a vested interest to make that claim. Without some kind of independent validation it soiunds like exxon denying pollution from its refineries.

what can be said about the better synthetic oils is that they have lower pour points, meaning that oil is likely supplied to the surfaces in need of lubrication faster than dino oils. this means they will have smaller times where NO lubrication takes place.

In all this discussion oils, not additives are discussed. It is know that additives can stick to parts even better than esters, so the base stock of the oil might not be the only factor. Still starting an engine and running it hard are two different situations. As RPM goes up greater demands are made on the lubrication properties for a given temperature. Its obvious that this is a complex subject, and BMW engineers know their cars as well or better than anyone. If they recommend warming the car up before running it hard, they are likely right. Only a fool would disregard BMWs recommendation vs an oil manufacturers advertisement. After all the oil manufacturer has nothing to lose and is driven by the one upsmanship of advertizing, but BMW has a vested interest in taking care of their cars that they stake their reputation on. If your car wears out prematurely, the oil company will not be blamed.
 
#53 · (Edited)
This discussion has bifurcated a bit in relation to the OP's question. One fork has been a discussion relative to the function of a lubricant at cold start, specifically the difference between synthetic and non-synthetic oil. The other has hinted at the reasons BMW focused on oil temperature rather than coolant temperature, and the benefits of giving more importance to oil temperature. In that regard, here's an article I posted on B*mmerforum using a different name:
Q: Why does my 335's engine take so long to warm up?

A: Actually it doesn't take any longer than any other engine. It just seems to take longer because you are being informed by the much more important engine oil temperature. Most temperature gauges tell you the temperature of the coolant ("antifreeze") in the cylinder head. This is NOT what you need to know, and here's why BMW engineers want you to know the oil temperature.
It's an old engine builder's maxim that cylinder heads make the power, the block only gets it to the wheels. It's the cylinder head which contains the compressed air/fuel mixture, and where that mix is ignited generating very high temperatures with relatively little heat transfer area. As a result the head heats up much faster than the more massive and better cooled block.
Cylinder head temperature is a very poor indicator of the block temperature! There are many rotating and sliding components in the block which may not yet have expanded to the proper size for optimal wear, and the minimization of stress. Yes, you can be getting lots of heat in the passenger compartment, maybe even defrosting that overnight ice accumulation. But the block could still be so cold that frost can be on its exterior!
The oil temperature is a much better indicator of the overall engine temperature. Your engine is NOT 'warmed up' until your oil temperature is in the correct range. Then you can be sure that your crankshaft has lengthened to the point where thrust bearing strain is reduced, that pistons are optimally sized to the cylinders, that journal clearances are dead-on nominal, and cylinder head gasket clamping force is correct. Then go ahead and drive it as it was designed to be driven, knowing that your oil temperature is telling you what you really need to know.

Most of us know that the coolant circulation is controlled by a thermostat. Well so is the oil circulation, at least through the oil cooler. BMW doesn't want the oil cooler cooling until the oil has reached a minimum temperature. I don't know this for sure but I believe it is about 220F. All this is not for the benefit of oil flow, any modern multi-vis oil is going to flow at even below zero temps. But what the engineers want is it to flow in an engine where the components have all properly sized themselves. (Which by the way is why we no longer have air cooled engines-like the old VWs. You just can't control emissions in an engine which has to operate over a hundred degree 'normal' temperature range.)
 
#54 ·
Actually the combustion chamber is closed on top by the head and on the bottom by the piston (remember that thing?), and by the cylinder walls.

The head's exposure is actually quite small since it has 4 valves. The 4 valves cover about 80% or the area with the head area at 20%.

The piston head (top) will heat up the fastest. Faster than the head which has water flowing in it and the cool, incoming air and fuel.

I've never heard that maxim because its not true.
 
#56 ·
Actually the combustion chamber is closed on top by the head and on the bottom by the piston (remember that thing?), and by the cylinder walls.

The head's exposure is actually quite small since it has 4 valves. The 4 valves cover about 80% or the area with the head area at 20%.

The piston head (top) will heat up the fastest. Faster than the head which has water flowing in it and the cool, incoming air and fuel.

I've never heard that maxim because its not true.
Frankly franka, I disagree on several points. The exhaust valves will heat the fastest and to the highest temperature. The pistons are cooled by oil splash, or even a jet of oil on some engines, onto their undersides. In addition there is heat transfer between each piston and the cylinder wall. The hottest area of the cylinder head casting will be between the exhaust valves because there is no coolant passage in this narrow area and it is sucking all the heat out of the exhaust valves during their seated time. I stick by my posting that the cylinder head is going to heat up at a much higher rate than the block.
To which maxim are you referring?
 
#58 · (Edited)
Of course the exhaust valves are the hotest. ...Da..

Only some engines have oil squirters to the bottom of the piston and usually just one. It is squirting oil that is much hotter and of much less volume than the coolant that is running thru the head.

The entire piston face is exposed to the heat source where the head's exposure is limited to what is left after the valve area is removed. Only about 20% of the piston's area.

They both are exposed to the same temperature but the piston has much more area exposed so it will absorb more heat.
 
#61 ·
Of course the exhaust valves are the hotest. ...Da..

Only some engines have oil squirters to the bottom of the piston and usually just one. It is squirting oil that is much hotter and of much less volume than the coolant that is running thru the head.

The entire piston face is exposed to the heat source where the head's exposure is limited to what is left after the valve area is removed. Only about 20% of the piston's area.

They both are exposed to the same temperature but the piston has much more area exposed so it will absorb more heat.
What is absorbed is one thing. What is transferred and what is retained is another. But what is the point you are trying to make which the above is evidence for?
 
#59 ·
Okay it's nice to worry about the engine. But if it's cold aren't the brakes,tires and everything else cold to? On a twisty road not much point having a warm engine and driving off the cliff.

If you've had a block heater it's nice how the car starts but you still can't drive like you want.
 
#60 ·
Okay it's nice to worry about the engine. But if it's cold aren't the brakes,tires and everything else cold to? On a twisty road not much point having a warm engine and driving off the cliff.

If you've had a block heater it's nice how the car starts but you still can't drive like you want.
Yes, that is correct. I think we are talking about what is best for the engine, letting it warm some or driving immediately.
 
#69 ·
There isn't one. If the engine temperature gets too high, you'll be alerted by a message in the IP (and iDrive if equipped).

The cooling system is electronic and is capable of shutting the pump off when the engine is cold to allow it to warm faster, plus it can also send you a warning that the pump has failed even before an engine overheat occurs. It can also run the pump with the engine off.
 
#70 ·
Yes, and the new M3 will disconnect the alternator and anything else when accerating hard to give it max power.
 
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