The Cold S65 - How to warm it up, Properly

[mxa121]

This thread is a discussion to help understand the S65 engine system and how it moves oil throughout to lubricate all of the internal components, i.e. bearings.
Let's keep it technical. It is OK to share how you warm up your car, but unless you include reasons why to do it that way, it doesn't really add to this discussion.

Let's go over some pre-requisites.
1. The S65 has extremely tight Rod Bearing clearances with multiple cases of engine failure due to lack of lubrication of the Bearings.
2. Because of #1, numerous threads exist to theorize a solution using different oil types, driving practices, and other things.
3. So far, there has been no objective results confirming a "solution" for the lack of bearing lubrication.

Now, how about some assumptions.
1. When the oil in the car is up to operating temperature, above 175 F, the bearings are being lubricated effectively.
2. During cold starting, and when oil is below operating temperature, below 175 F, the lubricating effectiveness is inadequate.
(I used 175 F based on the owners manual)

Quotes from the owners manual:
-Talking about launch control, identifies operating temperature, "after driving continuously for at least 6 miles"
-"When the engine is at normal operating temperature, the engine oil temperature is between approx. 175 F and approx 250 F"
-"if the vehicle is operated at temperatures below -4 F for extended periods, your BMW center will be glad to recommend an optimal oil."

With oil as thick as our 10W-60, temperatures very low, and an engine with super tight clearances throughout, what is the best way to warm up the engine and ensure proper oil circulation? My digging through the owner's manual did not prove fruitful. I am still unsure of what the optimal operating range is while cold.

I see many suggestions that keeping the RPMs as low as possible is the best method, but is it?
I think of the engine as a pump in this case, and increasing RPMs affect oil pressure, is this accurate?
If so, would keeping very low RPMs while the oil is thickest prevent proper lubrication due to lack of pressure?
Of course, common knowledge says more RPM = more engine speed = more heat, which is the enemy of the bearings in the first place.

What about the changing rev limit on the tachometer?
Is it fair to assume that the designers considered appropriate warm up RPM as anything that falls under the red on the fluctuating tach? If so, I could rev my engine up to 5k or so while cold without hurting anything. (this number, will of course vary depending on ambient temperature)

What about the well versed 3,000 RPM limit I hear so much about?
I followed this rule on my 335i and do the same on my M3, but I don't fully understand why. This would fall in line with "keeping the RPMs as low as possible" since driving an M3 below 3k RPMs is anemic since it revs to more than twice that.

Or is this all blasphemy that is unnecessary?!
All these failures are from a very small batch of production quality issues! All of these small variations described above are meaningless!

This is meant to be an academic discussion, not "another oil thread".

[AlpineE92M3]

I always let it warm up for at least 5-10 minutes, depending on outside temps. Just to make sure the oil is flowing through the engine, not sitting at the bottom of the pan (there's a lot of quarts in there). Still don't drive it spiritedly until operating temp is achieved. That's how I treat my cars, have never had a problem.

[chadwick]

Originally Posted by mxa121

Quotes from the owners manual:
-Talking about launch control, identifies operating temperature, "after driving continuously for at least 6 miles"
-"When the engine is at normal operating temperature, the engine oil temperature is between approx. 175 F and approx 250 F"
-"if the vehicle is operated at temperatures below -4 F for extended periods, your BMW center will be glad to recommend an optimal oil."

I wonder what the optimal oil for those conditions is...

[Jamaro]

You're over-complicating this.

Start it up, wait for cold cycle to end, drive away keeping rpms low until fully warm.

[Jamaro]

Originally Posted by AlpineE92M3

I always let it warm up for at least 5-10 minutes, depending on outside temps. Just to make sure the oil is flowing through the engine, not sitting at the bottom of the pan (there's a lot of quarts in there). Still don't drive it spiritedly until operating temp is achieved. That's how I treat my cars, have never had a problem.

That's not advisable. You do more wear to the engine letting in sit at idle. By driving right away the engine, gearbox, drivetrain is allowed to warm up more rapidly. That minimizes engine wear.

[5soko]

Originally Posted by Jamaro

You're over-complicating this.

Start it up, wait for cold cycle to end, drive away keeping rpms low until fully warm.

This..

[squartus]

Yep I always let it warm up in the garage about 5 min if it has sat over night then I keep it around 3k RPM until she is warmed up after 5-10 min on the road. Unless its summer then shes warm quick.

[Hujan]

My process:

-> Start engine
-> Allow to idle for at least 10 seconds before backing out of parking space/garage
-> Keep revs under 3k RPM until oil reaches ~210* F
-> Short shift the first few pulls after reaching 210* F

[e92zero]

Interesting discussion. I never got to ask any one about this but I would also really like to know the 'true' history of the 3000 rpm too. Here is something I read/come across a long time ago and is the best explanation I read of this 'magical' 3k rpm. It doesn't come from my own head so don't burn me on it if it's all bs.

The actual rpm of question is really 2880, relating to a harmonic frequency that happens at this rpm and is bad for engines. Note that there are bad frequencies through out the rev range of any engine. The higher the rev range of the engine, the more there are. The math goes like this: 2880 rpm ==> 48 revolution per seconds. Given that these are 4 stroke engine, dividing 48 by 4, you get 12 firing pulse per seconds. And somehow that results in the bad frequency. Supposedly it's every 1440 rpm based on the multiple of 6 firing pulse (if I still remember the math correctly). Each time the engine hit these rpm, it's not 'nice' and the engine should really be avoided to spin constant at any of these rpm. The 'cruising' gear supposedly take this into account and do not have the engine spin at this rpm when cruising.

The idea for the cold engine is to avoid crossing these rpms as much as possible and hence the not hitting the 2880 rpm ==> 3k rpm for ease.

I don't know if any of that is really true or still apply to today's engine and material. I also never went to dig deeper if this apply to all different type of engine configuration (I4, I6, V6, V8, etc) or the different block angle of different engines. I just followed it and keep it under 3k figuring it can't hurt. If any of the experts here is willing to shield some light to any truth to this and educate us, it would be great.

Thanks in advance. Cheers.

[Rupes]

Heat is a problem for the bearings, but couldn't an argument be made that higher heat = thinner oil that could squeeze in between the bearings? Once that oil is lubricating the bearing, isn't it hard for it to completely drip back into the oil pan?

I'm just thinking out loud - I feel like if I dipped something in oil and hung it out to dry, it would still have some oil lubricating it the next day.

[Petros]

i hate people that idle their car forever before moving. it burns gas, pollutes the environment, and actually puts more wear and tear on the engine. best practice is to start the engine, let it idle for a few seconds while you put your seabelt, adjust the seat, turn on radio, etc. then drive. use moderate throttle. no more than 30-40% throttle and upshift below 3000-4000 rpm for the first 10 minutes or so of driving. by then the oil is close to operating temperature and you can drive normally. it's not too complicated really.

[squartus]

Originally Posted by Petros

i hate people that idle their car forever before moving. it burns gas, pollutes the environment, and actually puts more wear and tear on the engine. best practice is to start the engine, let it idle for a few seconds while you put your seabelt, adjust the seat, turn on radio, etc. then drive. use moderate throttle. no more than 30-40% throttle and upshift below 3000-4000 rpm for the first 10 minutes or so of driving. by then the oil is close to operating temperature and you can drive normally. it's not too complicated really.

How about you keep your insults to yourself, this is a forum full of adults not a 2nd grade class room.
If you were really that concerned you the "environment" you would not be driving a car that gets 13mpg in town.

Now usually yes with modern cars you should not let idle long period of time to let warm up on a cold day. When its cold the fuel injectors are commanded to inject extra fuel, and your cars idle speed control valve is commanded to increase idle speed to prevent the engine stalling from a now richer mixture.
If your like me and have cold start removed then you bypass this process as far as I know, few min of letting the car run while you toss on shoes and shirt should not hurt a thing. Also if you live on a rather busy road like me you don't have to option of keeping it under 3k rpm when you leave, which is another reason I let it warm up a bit.

Manual does state you should not let car idle when cold for long period of time, I doubt it takes into the fact that they built a engine that can splode after 6,000 miles as well.

[Petros]

Originally Posted by squartus

How about you keep your insults to yourself, this is a forum full of adults not a 2nd grade class room.
If you were really that concerned you the "environment" you would not be driving a car that gets 13mpg in town.

Now usually yes with modern cars you should not let idle long period of time to let warm up on a cold day. When its cold the fuel injectors are commanded to inject extra fuel, and your cars idle speed control valve is commanded to increase idle speed to prevent the engine stalling from a now richer mixture.
If your like me and have cold start removed then you bypass this process as far as I know, few min of letting the car run while you toss on shoes and shirt should not hurt a thing. Also if you live on a rather busy road like me you don't have to option of keeping it under 3k rpm when you leave, which is another reason I let it warm up a bit.

Manual does state you should not let car idle when cold for long period of time, I doubt it takes into the fact that they built a engine that can splode after 6,000 miles as well.

How about you learn how to read properly? I didn't insult anyone. I said I hate people that idle their cars needlessly. That's not an insult. Learn how to read.

[1MOREMOD]

Free rev for 15 minutes. Keep between 6-8k.

[Petros]

Originally Posted by 1MOREMOD

Free rev for 15 minutes. Keep between 6-8k.

full throttle and downshifting as much as possible into the lowest possible gear also helps. makes the engine fully warm up in seconds.

[Jamaro]

lol

[e92zero]

lol

[wheatpaste]

Just get in and drive it easy until the oil gets up to temp. It's really not that complicated.

Prolonged idling doesn't really do much to warm up the motor or the gearbox anyway. However, I do understand people in colder climates starting the car a couple of minutes prior to driving. In reality a block heater that you plug in to keep the oil warm overnight is still a better solution than letting the car idle for long periods.

[rjd598]

Pretty sure in the manual it says not let idle. Could be wrong someone please correct me if I am.

[squartus]

Originally Posted by Petros

How about you learn how to read properly? I didn't insult anyone. I said I hate people that idle their cars needlessly. That's not an insult. Learn how to read.

Oh I read just fine, telling half of the above posters that you hate them for something silly is indeed an insult. I should not have to spell that out for you in such a manner.

But enouf of this, back on topic.

[Agent-GHQ]

Originally Posted by Hujan

My process:

-> Start engine
-> Allow to idle for at least 10 seconds before backing out of parking space/garage
-> Keep revs under 3k RPM until oil reaches ~210* F
-> Short shift the first few pulls after reaching 210* F

This is pretty much what the supplemental recommends on the initial start of the day.

[SenorFunkyPants]

I don't think there is anything wrong with letting your engine idle for a short while especially in a cold environment. The recommendation not to let your car idle on start up is most likely an anti pollution recommendation rather than an anti wear one.
The engine manufacturers start up procedure for the piston engined aircraft I worked on was to idle the engine until it reached a particular oil temp before exercising the prop to circulate the oil and no one is more particular about wear and safety than the aircraft industry.
Myself, for my garaged car, I drive off pretty much straight away but I keep the revs less than 2.5k until the oil temp moves off the stop...no high rpm until its at normal running temp.
I think the rev counter that indicates that you can run 6k rpm on cold oil is just plain idiotic...there are no doubt plenty owners who think this means they can do just that and hence the high bearing wear rate.

"I think of the engine as a pump in this case, and increasing RPMs affect oil pressure, is this accurate?"
This bit is not totally correct in the sense that the S65 has a volume controlled oil pump with an oil pressure relief valve set to ~90 psi....ie the pump has a flow rate target not a pressure target. You put in thinner oil you will get the same flow rate but a lower pressure.