Engine Warm-up and Cool-down

[RAY330I]

Hi buddy!
I just got my 330i Sedan a month ago... I really love it!

Do you think that we should let the engine warm-up before driving in a cold morning and let the engine cool-down after a hard run(before shutting down)? I read through the user manual, there is a statement saying that we should not leave our car idea for a certain period of time, this may cause damage to the engine.

Since I own a Turbo car before, I used to let the turbo and engine warm-up before driving and cool-down before I shut them down. What should I do to my new babe?
I am kind of confused here.......

If any of you know the right way to go, please let me know! Thanks!

Happy to join this 330i family!
Ray

With most new cars you can start your car and start driving right away without any problems

What you should do is accelerate slowly until the engine temp is at its normal operating range before you do any hard accleration. Try to keep your rpm's in the 2,000-3,000 range until the car is warmed up.

I'm not sure about cooling the engine off after a hard run though. Just drive an extra time around the block while taking it easy before you turn the car off.

[JuN14sCR]

i read it the user manual that you shouldn't just let your car sit when it's cold outside. instead, it recommended to start driving it at moderate speeds

[MarvelPhx]

Agreed; don't let it sit and warm up, just drive like a normal human and keep it under 3k rpm or so until its nice and warm.

As for cooldown, the radiator fans will stay on after you shutdown if they need to, but I always let my car idle for about 10 min with the hood up after serious hot-rodding... just my personal thing.

[david]

just going through old posts and noticed this one....
why is it a bad idea to let the car warm up on a cold morning? like when you turn it on and enjoy a cig and then get in?
any info i'd like...thanks
dave
________
20SE (http://www.chevy-wiki.com/wiki/20SE)

[traffic]

your motor doesn't operate "normally" while idling. raising your rpms (off idle) allows the oil pressure to build and basically circulates all the fluids. you should have oil circulating seconds after start up so you can drive away after about 20 seconds. you get 0mpg at just sitting. you get 10-15mpg while driving right away and it warms up faster.

for cool downs, use common sense. if you've been romping through the back roads (i'm talking really romping) then give it some time to cool. if you drive off the freeway and hit a rest area, give it an extra 30 seconds to cool the oil. if you're driving local roads, just shut her down. again, just common sense.

[david]

Thanks traffic. So am I actually doing any harm by turning her on and smoking a cig for 3 to 4 minutes and then driving slowly a bit? if so, i'll just turn her on and drive like you guys suggested!
________
Weed Bubblers (http://bubblers.net/)

[ME]

I don't think you're doing enough harm to be of concern. Especially during your ownership of the vehicle You're not doing any good either so why not start making progress? The only reason to warm your car up is convenience (heat or cool the interior.) And that only applies if you have a remote starter.

You should not let the car sit to warm up for a long time. But you should let it idle for about 30 seconds. This is required to let the oil which starts out at the bottom of the oil pan to circulate and lubricate vital parts before driving off and putting the engine under load.

The reason that it is recommended that you let the engine "cool down" before shutting off a turbo car is because the rapid cool down from just shutting it off causes the oil to solidify inside vital oil passages such as the turbo oil line. This is known as "coking". This is not a real problem for normally aspirated cars because of lower operating temperatures. Also, synthetic oils are resistant to this effect.

I usually let it idle until the rmp drops to 600-700 rpm which takes about 30-40 seconds in my car.

[traffic]

reasons to start motor and not drive off:

1. you're very used to driving your '85 land rover with manual choke that bucks and kicks until warmed.
2. you refuse to rev your engine past 1000 rpms until the temp needle is toward the middle.
3. you've never owned a 2-stroke motor.
4. you used to be a truck driver and diesels can idle for hours or days.
5. there's this cute gal near your car and you need as much pose time as possible in front of the car.
6. you're a chain smoker, but have a big "no smoking" sign in your car.

it used to be that performance engines were not tuned for idle or even putting around town. they would often foul plugs and generally not run very well if 'babied'. these (our modern) motors, however, are pretty much bullet-proof and are made for a wide range of owners and driving habits.

i can't idle my '94 ducati for very long or else it'll 'gum' up the motor. i have to drive off as soon as i can hold a fast idle. it runs a lot better when i'm abusing it. funny about italian motors...

<font size=-1>[ This Message was edited by: traffic on 2002-11-27 12:55 ]</font>

[ME]

You'd be suprised at how passionate people are about warming their cars up in the driveway. To think grown, seemingly intelligent adults with $60k M3's do this every morning. I can understand if you do it for convenience (warm up/cool) but to be so delusional as to think it actually helps the engine, ay caramba!

[traffic]

on cold mornings, here is my startup procedure:

1. open door.
2. press memory #1 on seat (wife is 6" shorter and also drives the car)
3. get in and close door.
4. start motor.
5. turn bun warmers on.
6. fasten seatbelt.
7. drive away.

it's about 30 seconds from step 4 to step 7.

heated seats kick in after 90 seconds. warm air starts blowing after about 3 minutes. this is an awesome winter car.

[david]

traffic,
I fall under category 7...chain smoker...big no smoking sign. so my car gets a 3 minute warm up and hot air is blowing when i get in. i doubt i'm doing any harm to it at all. plus i've got an hour long commute, and i'm not pullin over just for a nic fit. hahahah
dave
________
FERRARI 250 GTO (http://www.ferrari-wiki.com/wiki/Ferrari_250_GTO)

As in my earlier post...Although it is commonly called "warming up the car", this is not technically necessary. What you are really suppose to be doing in the 30 seconds or so of warm up is allowing the oil to circulate and lubricate vital parts before putting load on it.

[FRANCO]

Once I get in my car, I start the car and IMMEDIATELY put it into reverse, then drive, and I drive off keeping it under 2K (that's my thing) until the water temp is in the middle, and I still keep it under 2K for like 3-5 min. after the water temp reaCHES the middle. As for warming down when I give Stacy the old German tune-up, once I enter my neighborhood (I live in one of those enclosed neghborhoods)I just gas it and keep it under 2K again, sometimes not even stepping on the gas, then when I get to my driveway, I park and keep the engine running for a good minute until I finally shut her down. When it comes to Stacy, I'm not taking any chances

Oh yeah, recently I put some STP FULL Fuel System Cleaner in my car, iut's suppose to clean out the injenction system, intake valves, etc... Anyway, before I put it in, I was going at a steady 23.8 mpg, then after I put the STP in, my mpg's shot up to 28.3!! Anyone have thoughts on this?

[Darius]

Are the injector cleaners safe for our cars? I have never used it on my BMW. Wow it did improve your gas milage a lot.

[antetr95]

I drive off as soon as I turn on my engine, but keep the RPM under 2K for about 3-4 miles or so until the water temp guage reaches the middle. Before turning my engine off, I wait about 30 sec or so depending on how hard I've been driving, then open the hood of my car to allow faster cooling down of the engine.

I don't think BMW recommends adding any engine additives. I think it may damage some engine sensors.

Those of you driving off right away while keeping it under 2k RPM need to ask yourselves this...

1. In the morning, where is all the oil? That's right, in your oil pan.

2. What has to happen for all the hundreds of engine parts to get lubricated and protected? The oil has to get pumped up through all the little hoses and passages.

3. What happens when you drive off at 2K RPM before NUMBER 2 happens? You wear out your engine parts at a lower RMP that's all. Metal rubbing on metal is never good.

Interesting that many take the cooling down process much more seriously. In an average normally aspirated car, extra effort to cool down the car such as opening the hood is not necessary. If the heat was a problem the engine would have fried before you even got home.

[antetr95]

<font size=-1>[ This Message was edited by: antetr95 on 2002-12-01 13:02 ]</font>

[antetr95]

On 2002-12-01 03:37, Anonymous wrote:
Those of you driving off right away while keeping it under 2k RPM need to ask yourselves this...

1. In the morning, where is all the oil? That's right, in your oil pan.

2. What has to happen for all the hundreds of engine parts to get lubricated and protected? The oil has to get pumped up through all the little hoses and passages.

3. What happens when you drive off at 2K RPM before NUMBER 2 happens? You wear out your engine parts at a lower RMP that's all. Metal rubbing on metal is never good.

Interesting that many take the cooling down process much more seriously. In an average normally aspirated car, extra effort to cool down the car such as opening the hood is not necessary. If the heat was a problem the engine would have fried before you even got home.
Hmmmm. The BMW manual says to drive easy to warm up the engine instead of waiting and idling your car. Unless you are BMW certified engineer, who builds our engines, your points are merely opinions and not fact. Doesn't synthetic oil possess properties that allow a film of oil to bind to engine parts after the engine is turned off resulting in non metal-metal rubbing. Also, opening the hood of my engine allows the heat to escape faster than if the hood was closed. You don't have to be a phycisist to know that. I'll do whatever it takes to take care of my car. Whether opening our hoods is necessary or not is your opinion but no thanks. We all love our cars and we may do things that are out of the ordinary and thats why we are members of this site to share our passion.

Jess

<font size=-1>[ This Message was edited by: antetr95 on 2002-12-01 13:05 ]</font>

<font size=-1>[ This Message was edited by: antetr95 on 2002-12-01 13:26 ]</font>

[FRANCO]

about my mpg's, it went back down to a steady 24.8, from the 28 I posted earlier. Guess it's only a temporary thing. ah well.

Jess,

1. In my earlier post I suggested letting the car warm up for about 30 seconds not a long time. I believe this is consistent with the BMW manual.

2. The bonding of synthetic oil to metal is a real benefit as you stated. However, this is diminished the longer the engine is off. The real benefit of synthetic oil is that is flows to get to critical parts faster during cold starts.

3. Yes opening your hood allows heat to escape faster but why? It doesn't do any harm. The car is a lot hotter when you are driving and we don't drive with our hoods open. But then as you stated, why not?

4. Yes my post was just an opinion. We all love our cars and have unique ways of taking care of them. But someone, perhaps not as experienced as you, started the subject and I offered an opinion. Isn't that what this site is all about?
While I did not mean to imply that your methods are incorrect, I would like to add that I am an ASE certified mechanic (past job while in college) and am presently working as a consulting engineer for Pratt-Whitney speciallizing in heat transfer. Perhaps you have heard of the F-16.

[ME]

On 2002-12-01 03:37, Anonymous wrote:
1. In the morning, where is all the oil? That's right, in your oil pan.

And where is all that oil after about 5 turns of the crankshaft? Under pressure and circulating...

2. What has to happen for all the hundreds of engine parts to get lubricated and protected? The oil has to get pumped up through all the little hoses and passages.

Like I said, you have oil pressure virtually instantly. Oil pressure means oil circulation. And I don't know of any hoses in the oil system of a car...

3. What happens when you drive off at 2K RPM before NUMBER 2 happens? You wear out your engine parts at a lower RMP that's all. Metal rubbing on metal is never good.

Wrong, see above. And this thread was about warming the engine up, not waiting for oil pressure.

Interesting that many take the cooling down process much more seriously. In an average normally aspirated car, extra effort to cool down the car such as opening the hood is not necessary. If the heat was a problem the engine would have fried before you even got home.

Interesting that you're so rational about cooldown but so irrational about warmup. I agree though, the only thing dumber than warming the car up is cooling it down...

And BTW, turbine engines have nothing in common with piston engines.

Please let me clarify. You do not have "instant" lubrication when you turn on the engine. You have instant oil pressure as soon as the oil pump starts to turn. It takes some time, although a very short time, for the oil to reach the upper parts of the engine. Oil does not travel at light speed and the last time I checked there are a lot of crevices and obstacles in a typical engine. Hence the saying "most of engine wear occurs at start up".

As Jess said, oil will bond to the metal parts and help to prevent metal-to metal wear. However, this is only really effective when the engine is not under load as during idle. When the engine is under load you need a film of oil so that the parts "float" without grinding on each other. Those of you into racing will know that Porsches and M3's, to name two, have special baffles in the oil pans to prevent oil starvation during high g-force turns. This oil starvation happens for very brief periods when the oil sloshs to one side of the oil pan and the oil pump starves for oil. This brief period is usually only a couple of seconds, much shorter than the 30 second warm up we do, but yet the engineers took the time to design special oil sumps. If they believed in the oil bonding to metal rather than an actual oil film is enough when the engine is under load, they would not have bothered. The 30 second warm up is just a general guideline since it takes that long to buckle up and get it in gear anyway. I'm sure the actual time for the oil to circulate is much less as you mentioned and it varies with each car. My point is not how long to warm up the car but only that you should allow adequate time for the oil to circulate before driving off and putting the engine under load. Honestly I think 15 seconds would be plenty. When the BMW manual says they do not recommend a long warm up, I believe they mean a long long time not just 30 seconds or a minute.

I think a lot of people are led to believe in the benefits of oil-to-metal bonding as seen in the Slick 50 and Duralube commercials. While there are really benefits, these commercials are misleading because the engines in their tests are not usually under load and are not expected to last 100k miles. We all love our cars as can be seen from your passionate responses. But I would not do a Slick 50 test on my BMW so that I can save 30 seconds every morning. To each his own.

[traffic]

i have 112k miles on my gti. no oil burning, dripping, blow-by. typically drive near redline on a daily basis. but change oil every 3k miles AND i use petroleum oil (i don't buy into the grand benefits of synth...but i put it in the 330i). i have always driven off after i've buckled in and made any critical adjustments (like the proper radio station.) the point is, that's about enough time to have oil flowing. ok, so i only let it idle 23 seconds instead of a full 30. the scoreboard says i'm doing just fine.

as for your racing analogy, how much heat is generated during a race? answer: a lot. way more than you'll ever experience in street driving let alone at cold start up. no let me rephrase that "WAY MORE THAN YOU'LL EVER EXPERIENCE IN STREET DRIVING." lubrication and heat dissipation is much more critical during these times. it's like comparing the structural integrity of your wing in the hanger versus pulling a 6g turn. ok...not quite the same, but you get the idea.

anyway, before you feel that i am attacking you. i'm not. i'm glad you have experience with maintaining jet engines. that's great to see people with such technical background that have chosen the 330i for what it is and can do rather than just a bmw badge. thanks for your inputs.

[david]

well, i'm not sure about the any Jet engines, but i am a pilot. In all the planes I've flown, there's a oil temperature, and an oil pressure guage. the oil temp usually rises slowly, the oil pressure a lot faster, but still not within a second or 2 after engine startup. in either case, there's no need to argue over who is right or wrong, I think one of the original questions of this post was wether or not any damage is being done as a result of a 3 or 4 minute startup. so i guess that even though some say it's not NEEDED, it doesn't hurt any to idle for a while. you're car is idleing at every stop light and drivethrough anyway.
Hey Anonymous: what F-16 have you worked on? what squadron?
________
THE GIRLS NEXT DOOR ADVICE (http://www.tv-gossip.com/girls-next-door/)

[fcotanis]

I have not posted in here thus far because really everybody is expressing their opinion. We do not have the design blueprint of the 330i to explain the reason why the BMW designer thought that cold engine idling is a damaging business.

The only assumption I can make is that the 330i is a ULEV vehicle and to achieve that the rpms are kept very low while idling and hence it might be the case that right after startup the engine could go a little bit oil hungry if we let it sit instead of giving it a light-moderat stab of the throttle.

ANONYMOUS: Tremendously, extrordinarily logically balanced posts! I think you are an awasome person and writer. Please register and stick around to give us more of your thoughts!

I am thrilled and proud to see people like you post on this website. You guys are what makes this site so special. If you have not registered please do so so we can know who is posting. So please please please assign yourself an identity.

God Bless!
Thank you God,
Filip

[Darius]

Ok since everyone is posting here. Here is my 2 cents. I try to follow the manual which says that we should not let the car warm-up at startup. It usually takes me 15-30 seconds to adjust before I drive off. I got 70000 miles on the engine and there is absolutely no oil leak (knocking on the wood)
I also have a neighbor with 1995 325i who every morning warms-up his car for at least 15 minutes with his foot on the accelerator, reving up the engine pretty loud I would think at least 4-5K RPM. It seems so dumb to me. Hey but he is happy with his car he does not have any engine problems that I know of. As for the anonymous guy, take Filip's advise and register. You will like it here. We love to see all different opinions /forums/images/smiles/icon_smile.gif

[antetr95]

Anonymous,
You make very valid points and support them well. And yes, BMW is not clear how long to warm up the engine, but 30 seconds as you've implied sounds good.

I did not mean to sound as if I was attacking your posts earlier. A lot of us here are not professional mechanics/engineers and the tone of your reply seemed just a little condescending (no offense) to us regular joes. I actually welcome constructive criticism as long as they are not demeaning other posters.

Just as the others have mentioned, consider registering. You'll be glad you did.

Jess

[ME]

On 2002-12-04 13:28, david wrote:
...the oil pressure a lot faster, but still not within a second or 2 after engine startup.

I assume you're talking about piston engines. I'm a pilot and A&P mechanic and can tell you the oil pressure guage is not an indicator of how quickly oil pressure builbs. The reality is that the pressure builds almost instantly, after a few rotations of the crankshaft which is not even 2 seconds. It would be practically impossible to drive off before you had adequate pressure or flow. I get in, start the car, buckle up and go. 10-15 seconds tops. I believe how you drive the car when it's cold has a much greater impact on engine longevity. And BTW, 30 is a long time to sit in a car when you're ready to leave or get out. Next time you arrive at your destination time off 30 seconds just sitting there, it's a long time!

[david]

Me,
Thanks for the info. i learn something new every day. so how come the oil pressure gauge is not a good indication of how fast oil pressure builds? isn't that what the guage is for?
Thanks,
David
________
IOLITE VAPORIZER (http://vaporizers.net/iolite-vaporizer)

Wow didn't mean to cause so much contraversy. Thanks guys, I'll register soon, just lazy that's all.

David, I am a consulting engineer for PW not military.

[ME]

Because the oil in the line leading up to the transducer never really circulates because it's a "dead end street." Consequently you get a lot of gunk building up there. So when the engine starts it takes a while for the pressure to reach the transducer. In cold climates mechanics will actually fill that line up with solvent so that you get a quick oil pressure reading. I'm talking about aircraft engines where they use antiquated junk. Automobile guages may not have this problem.