Engine Warm-up time

"All our final decisions are made in a state of mind that is not going to last."
-Marcel Poust

Originally Posted by desertdriver

I have a friend who has a 328i, and he runs it pretty hard right after startup, and it doesnt get that cold here. He bought the car new and it burns oil, a quart every 3-4K. My 335 doesnt burn any oil at all. I have changed oil at 5k(1st), then at 7K intervals, and it burns no more than 1/4-1/3(7K) of a quart. this could be due to differences in break-in, but running the car hard at startup could also make the car burn more oil by increasing wear.

My 328i has never needed any oil between changes. I was reasonably good during break-in (ED on the Autobahn excepted) and don't cane it cold. Pays off in the long run. Leasers feel free to ignore the above

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.)

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.

[QUOTE=desertdriver;3640647][QUOTE=franka;3640232]

But you forgot to consider that the source telling you this was basically an advertisement.


I didn't forget anything as it was not in an advertisement.

Originally Posted by franka

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?

Originally Posted by DSXMachina

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?

Yup, I can agree with this. Exhaust valves are the hottest part of the engine, some are made of inconel for this reason, to take the heat in high performance applications. Aluminum, steel and cast iron are inferior to inconel in taking high heat.

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.

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.

Originally Posted by Nicola

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.

Originally Posted by franka

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?

Originally Posted by DSXMachina

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?

He still appears to be struggling with the transfer of heat out of the piston to the block. then there is the shedding of heat by the block.

Originally Posted by Nicola

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.

Quite true. On even coolish mornings my tires tend to tram line until warm.

Originally Posted by DSXMachina

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?

From your prior post below..specifically " its the cylinder head which contains the compressed mixture..."

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.

Its the head, piston and cylinder walls which contain the compressed ...etc. Its not just the head.

What is the best way to warm up the cabin to defrost windows & such, since we should not sit idling?

Originally Posted by stuknnj

What is the best way to warm up the cabin to defrost windows & such, since we should not sit idling?

Besides parking in a garage?

Originally Posted by anE934fun

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'.

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.

This may be an incredibly stupid question, but I cannot even manage to find the engine temperature gauge. I have a 2006 330xi...any ideas? Thanks!

Originally Posted by karlmalden

This may be an incredibly stupid question, but I cannot even manage to find the engine temperature gauge. I have a 2006 330xi...any ideas? Thanks!

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.

Yes, and the new M3 will disconnect the alternator and anything else when accerating hard to give it max power.

Originally Posted by stuknnj

What is the best way to warm up the cabin to defrost windows & such, since we should not sit idling?

Good question - bumping

This morning had a nice thick layer of frost left idling for a few minutes - guess that's a bad thing - what to do?

Originally Posted by jwac

There isn't [and engine temp gauge].

Whoa, really? Dang, things have changed a lot since my E46. I'm going to be one confused puppy when my E93 gets here it seems.

Speaking of which, the only manual I can find online for the E93 is two years old. Anyone have a link to a new version of the manual? I like to read up on things before I pick up the car. Since I'm apparently in for quite a shock of changes, I definitely want to read up before delivery.

Originally Posted by franka

i would like to see the exact wording in the manual.

read the manual of your car. It's in there.

Originally Posted by nhhiep

read the manual of your car. It's in there.

Aren't you the little wise a*s.

The post was not addressed to you, and the thread is not yours. So when did you become authorized to speak for the poster?

More to the point my little friend, my question was about the poster's X3, and not an E39, and since I do not carry a Bentley for all models I had to ask. Or maybe you can tell me what the X3's manual says?

Originally Posted by Black 335xi

This morning had a nice thick layer of frost left idling for a few minutes - guess that's a bad thing - what to do?

Buy a scraper. I keep a small one in the door pocket. One side is a scraper, the other side has a rubber blade.