Warm up time

[SQ13]

Is the 3k figure stated in the manual, or did someone come up with that and we just follow along with it? Why 3k? Just curious. I’ve been doing it since the day I got my car, but I never really questioned why it’s 3k and not 3.5k or 4K.

[CrisSilberGrau]

Oh another one of these, good cause I changed my routine.

Strat driving right after the rpms drop a bit from start, usually 10-20sec, then slowly rev to 3k in 1st to give my neighbors S54 rasp good and proper.

[Tbonem3]

Is the 3k figure stated in the manual, or did someone come up with that and we just follow along with it? Why 3k? Just curious. I’ve been doing it since the day I got my car, but I never really questioned why it’s 3k and not 3.5k or 4K.

I like that area of the powerband because you're not lugging and you've got good torque, but it's not too many RPMs, so less wear, while oil reaches temp. I don't try to hit exactly 3k anyway - just somewhere around 2.5-3k. Also, you don't engage Vanos yet, which I assume works better once oil is warm - just a guess.

I do believe, however, that BMW has specified 3k RPM as a good place to get to for a sustained period if you've been in traffic for a while/stop and go/low rpms

[Tbonem3]

Good point about rasp Cris If you stay at 3k while warming up, you won't produce that hard rasp we make at what, like 3.5k or so?

[CrisSilberGrau]

Good point about rasp Cris If you stay at 3k while warming up, you won't produce that hard rasp we make at what, like 3.5k or so?

Rasp comes on full bodied at 2.2-2.5k with oem Uros and scza, beautiful tone and loud for my setup . Those first few hundred feet when cold I adore.

[FBloggs]

I wait 30 secs, then drive.
The gearbox is baulky until it warms up so there's little point in hurrying.

[Tbonem3]

Rasp comes on full bodied at 2.2-2.5k with oem Uros and scza, beautiful tone and loud for my setup . Those first few hundred feet when cold I adore.

Oh that early? I'll have to pay attention next time, I thought it was above 3k. Come to think of it, I think there are two spots in the powerband where rasp is pronounced.

[erickhoyos]

Damn, everyone here is taking that extra step to make sure the engine is lubricated well on cold starts meanwhile I’m here like “if I’m not ready, neither is my car” LOL.

[mrgizmo04]

The factory S54 oil pump has a regulated pressure of 4 bar (58 psi). On cold start idle oil pressure will be 4 bar (58 psi) and when warm driving at higher rpm the oil pressure will also be 4 bar (58psi).

Dan, I don't think that at idle the pressure will be that high. At idle the pressure will probably be closer to 10 or 20 psi, and drop a little as the oil warms up and viscosity drops. Given that the oil pump is mechanically driven, it can't have max flow at idle, there is just not enough oil volume being pumped through the fixed size/area oil tubes/pipes/galleys/etc to create that much pressure. Above 3k rpm, I can see it building to the max.

It's similar to washing a car with a hose and holding your finger over the end of the hose to constrict the flow to reach farther away. That's what pressure is, flow through a restriction. But there has to be enough volume flow, otherwise if you put your finger over the hose, you will stop the flow completely, and you will have to go back to the faucet valve and open it more.

So starting the car from cold and idling will see a bit higher pressure than idling a warm engine because cold oil will have higher viscosity and therefore run at slightly higher pressure. After the car warms up and oil thins, running it at higher rpm gets you to the proper pressure.

I think that is why these cars require such thick oil, to protect the engine somewhat running it cold, but also that the pump doesn't really put out that much pressure (60psi is not a lot) when hot and running it to 8k redline, so having ticker oil helps keep the surfaces protected with subpar oil pressure from the mechanical pump.

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[Flat-Six]

I don't/never let it sit and idle. I crank it up and drive off, and don't exceed 4500, usually 4K in the M3, until I have full oil temp (170-180). If I am in a position where I am waiting on something/someone after starting cold, then I take it up to 2K immediately and hold until I am ready to drive off. Engines like to warm up quick...

[ELEM3NT]

Thought I read the warm up lights are tied to water temp and not oil temp...I've always used oil temp as the primary guideline.

[Pavlo]

The procedure that most people here follow is the best one from my understanding. The reason for it is that the sooner the engine comes to operating temp, the better its off.
On a cold idle, the AFR are pretty rich and a lot of unburned fuel ends up making it into your oil, reducing its life (and the life of your engine). So start it up and casually begin your drive.

Another consideration with warming the car up is that your gearbox and differential are still cold, so light driving helps with getting everything up to temp together and not just the engine.

[Jimbo's M]

Thought I read the warm up lights are tied to water temp and not oil temp...I've always used oil temp as the primary guideline.

They are. I personally don't get on it til the oil temp reaches the first dot which is considerably longer than all the lights going out..

[mrgizmo04]

The procedure that most people here follow is the best one from my understanding. The reason for it is that the sooner the engine comes to operating temp, the better its off.
On a cold idle, the AFR are pretty rich and a lot of unburned fuel ends up making it into your oil, reducing its life (and the life of your engine). So start it up and casually begin your drive.

Another consideration with warming the car up is that your gearbox and differential are still cold, so light driving helps with getting everything up to temp together and not just the engine.

Side note for fun, tranny input shaft is spinning and warming up as the engine idles, so the only thing that is not getting warmed up is the diff without driving.

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[mrgizmo04]

They are. I personally don't get on it til the oil temp reaches the first dot which is considerably longer than all the lights going out..

Water and glycol transmit heat faster and better than oil, so "coolant" warms up faster. There is a way to manually adjust the degrees at which each of the orange segment lights goes off via Martyn's tool.

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