Is there any practical benefit to letting a passenger car oil warm up before driving?

[930.engineering]

My car, a BMW M240i, will idle at about 1300rpm after every start. The engine then will slowly decrease the revs until they reach ~750rpm. The reason that the engine is programmed to do this-regardless of the engine temperature-is to ensure that oil is getting to the turbo quickly.

Speculation. I agree with jeepman and edyvw, the main reason is to heat
up the cats quicker. Same on most if not all gas cars last two decades.
.

 

[4WD]

As @jeepman3071 said, oil is there in no time and reason are catalytic converters.
But, IMO BMW should be driven moderately far longer than a mile. They have really big oil sumps and while coolant in BMW warms up really fast, oil lags a lot.
In average BMW at let’s say 30 degrees you need at least 7-8 miles for oil to reach operating temperature.

And even 0W20 is like molasses in Florida at start up - or so I read that somewhere

 

[Slow Car Sport Mode]

Speculation. I agree with jeepman and edyvw, the main reason is to heat
up the cats quicker. Same on most if not all gas cars last two decades.
.

This is also why you see exhaust manifolds wrapping around oil filters or close to or things like this, the idea is the exhaust will heat up pretty fast and hopefully in turn heat the oil as quickly as possible.

 

[RDY4WAR]

Speculation. I agree with jeepman and edyvw, the main reason is to heat
up the cats quicker. Same on most if not all gas cars last two decades.
.

Emissions is a large part of it. A cold engine burns dirty because of poor fuel vaporization and weak catalytic converter performance. If you look at the spark tables for most all EFI engines, the spark timing is usually retarded quite a bit during that high idle. It'll be as little as 4° advance. This is beneficial to engine warmup for 3 reasons...

1. It makes it so the air/fuel mixture is still burning when the exhaust valve opens which "cannon fires" the cats to get them working efficiently sooner.
2. It dumps a lot more heat into the exhaust ports and thus the coolant flowing around the exhaust ports.
3. It increases residual cylinder temperature which aids in fuel vaporization.

Doing this also means the engine idles like crap so the idle rpm is raised during this rapid warmup cycle. Once that cycle is complete, somewhere between 10 seconds to 2 minutes, the idle rpm goes down and the timing advances to 15-30° for smooth idle and good response. You'll usually notice an audible change in exhaust tone when this happens. The car is ready to drive at this point.

 

[edyvw]

This is also why you see exhaust manifolds wrapping around oil filters or close to or things like this, the idea is the exhaust will heat up pretty fast and hopefully in turn heat the oil as quickly as possible.

Hmmm, that should not be the case. Exhaust manifolds run super hot. For quicker warm-up usually, heater exchange boxes are used. For example, in BMW coolant line goes through oil filter housing in models without heat exchangers and those with regular radiator coolers.
Newer BMW's have both heat exchangers (to warm up oil faster) and oil cooler radiators.

 

[Slow Car Sport Mode]

And even 0W20 is like molasses in Florida at start up - or so I read that somewhere

Any motor oil is too thick at start-up, yes.

 

[Slow Car Sport Mode]

Hmmm, that should not be the case. Exhaust manifolds run super hot. For quicker warm-up usually, heater exchange boxes are used. For example, in BMW coolant line goes through oil filter housing in models without heat exchangers and those with regular radiator coolers.
Newer BMW's have both heat exchangers (to warm up oil faster) and oil cooler radiators.

I was thinking specifically of a Subaru EJ253 engine for reference, I had thought this is why it was done and the principal more widespread and adapted but if not, okay, I stand corrected.

Picture for reference.

 

[edyvw]

I was thinking specifically of a Subaru EJ253 engine for reference, I had thought this is why it was done and the principal more widespread and adapted but if not, okay, I stand corrected.

Picture for reference.View attachment 85419

Oh, it must be fun changing filter
I think Subaru is limited bcs. engine design.

 

[Slow Car Sport Mode]

Oh, it must be fun changing filter
I think Subaru is limited bcs. engine design.

Well for people with an EJ253. I would advise them to not change that one hot. Unless they have some kind of an oven glove.

Always wondered when Subaru would ditch the Boxer schtick. I'm sure they would be better served with a standard inline. Plus the new 86/BRZ I do not know if is boxer OR AWD.

But even those engines idle the engine high, you are only supposed to move the car when the RPMs drop down...

 

[edyvw]

Well for people with an EJ253. I would advise them to not change that one hot. Unless they have some kind of an oven glove.

Always wondered when Subaru would ditch the Boxer schtick. I'm sure they would be better served with a standard inline. Plus the new 86/BRZ I do not know if is boxer OR AWD.

But even those engines idle the engine high, you are only supposed to move the car when the RPMs drop down...

New 86/BRZ is 2.4 boxer naturally aspirated. RWD of course.

 

[sk_pete]

Always wondered when Subaru would ditch the Boxer schtick.

awd+boxer is their mantra, something that makes them unique on market.
without it, it´s just another honda or whatnot.

 

[R1jake]

I warm up my car even in the summer for 2 mins and winter 4 mins or so before I drive off. I do this to let the pistons expand a bit before getting load, as I have a high boosted engine. I have seen some junkyard Hyundai engines with bad piston skirt wear. Just trying to keep my highly thrashed engine in good shape to take it's long term beating.

This is similar to what I do, the Toyota Yaris has a cold temp light that comes on when you start the car. In the summer it can go off as quick as 1 min or so if it’s super hot out. Usually more like 2 min. The winter months it takes a good 4/5min to go out. My ford van 5.8l I let run a good 5 min before taking off usually, that thing takes a good 15/20 minutes to fully warm up if you just let it sit and idle. It has a massive cooling system.

 

[demarpaint]

This is similar to what I do, the Toyota Yaris has a cold temp light that comes on when you start the car. In the summer it can go off as quick as 1 min or so if it’s super hot out. Usually more like 2 min. The winter months it takes a good 4/5min to go out. My ford van 5.8l I let run a good 5 min before taking off usually, that thing takes a good 15/20 minutes to fully warm up if you just let it sit and idle. It has a massive cooling system.

I have parked in my driveway for about three months now my father's 2013 Legacy, I hate the car but that's another story for another day. It has a blue thermometer that lights up when the engine is cold. We've been in the teens a few times the past couple of weeks. I start the engine idle it for about 30 seconds and drive nice and easy. It takes ~ 3/4 of a mile of driving with a few stop signs and one traffic light for that blue light to go off. Not sure what Subaru was thinking, there's no heat coming from the vents when that light goes off. If the uninformed thinks that when that light goes off the engine is "warmed up," or warm enough/safe to push hard or beat on they'd be dead wrong imo.

 

[Danimal1q2w3]

Today it was -20f and after a 20 min warm up the car was still not as hot as I wanted it to be when I got in, and I think it took a while for the transmission fluid to heat up. Took about 20 min of highway driving to start feeling normal. Days like this are rare, but it’s why I run a 0w.

Edit: spelling

 

[Slow Car Sport Mode]

Today, 15°F but feels colder cold start, I turned the key and started the engine and let the engine idle maybe 5 to 10 seconds before I was in drive and driving away.

I have the luxury of a nice 2 or 3 minutes slow driving before I'm doing any kind of speed above 55 mph. But I'm still essentially turning the key and going.

No issues... heat will take between 5 to 10 minutes though.

 

[RyanY]

I was thinking specifically of a Subaru EJ253 engine for reference, I had thought this is why it was done and the principal more widespread and adapted but if not, okay, I stand corrected.

Picture for reference.View attachment 85419

I'm not sure which is worse - the wraparound exhaust or the sharp point/flange near the edge of the filter. These engineers are clearly not the ones changing the oil!

 

[ZeeOSix]

I'm not sure which is worse - the wraparound exhaust or the sharp point/flange near the edge of the filter. These engineers are clearly not the ones changing the oil!

Built in torture devices.

 

[FastLane]

It’s was -33C here the other night. My truck was at the airport for 5 days. It started up just fine. It was at low idle in a minute. I cleaned the snow off of it which took about five minutes. I drove off slowly. I stopped at the first stop light approximately 1km away. Coolant temp was coming up and trans temp was up to -12.

220,000 kms on the 4.8 V8. Doesn’t use any oil. Hasn’t blown up yet….

 

[CleanSump]

The only reason to warm up the engine during Winter is so your wife person doesn't complain.
Turn the heated seats on High. They take a couple of minutes to get warm enough to penetrate a coat and jeans.

 

[sk_pete]

They take a couple of minutes to get warm enough to penetrate a coat and jeans.

minutes really?
i keep my seat at 2, because at 3 i smell bacon and eggs.