Not reaching 220F oil temp in efficient mode

[tjjmx]

My 2018 M3 with only 35k miles been running at 180F coolant and 210F oil temperatures on efficient mode the last 10 times I’d driven. Before it was always running between 220 to 225F on both temps.

I got the BimmerLink app showing live temps while driving. I usually hit the freeway with freeway speeds before fully warmed up. Never an issue, but when this started happening first couple of times after I got off the freeway the temperature would get back to normal at both 220F. Now it just stays at 210F oil and 180F coolant.

And last few times when I select sport+ mode the engine oil drops from 210 to 200F and coolant down to 160F. So I think the coolant thermostat isn’t an issue, or is it? Thanks, any help appreciate it.

[Groganrocket]

Sports plus put the car is max cooling that’s why is getting cooler.

[FrankMstein]

If you changed oil brands that could be a factor. Some run cooler than others. What are you using?

[jagus]

Which petrol do you use? I had that behaviour when using low octane petrol (95), when back to high octane (98), the temperatures are right

[tjjmx]

Car is complete stock and using BMW LL 0W-30 oil with 91 octane gas in California.

Last oil change was 3k miles 6 months ago ago and this just started happening ~ 400 miles ago.

[jagus]

Originally Posted by tjjmx

Car is complete stock and using BMW LL 0W-30 oil with 91 octane gas in California.

Last oil change was 3k miles 6 months ago ago and this just started happening ~ 400 miles ago.

Increase octane, 91 is too low

[tjjmx]

Originally Posted by jagus

Increase octane, 91 is too low

That’s the highest common gas stations in California goes up to. Was always at 220F or needle right on the marker on the oil temp gauge, the first marker that’s left of 250F.

[NSX2M4]

I think you're way overthinking this. If you're not tuned, have oem parts, and recommended fluids, I would not even blink an eye at this.
If you're tuned with a bunch of bolt on's, welcome to the rabbit hole.

[tjjmx]

Originally Posted by NSX2M4

I think you're way overthinking this. If you're not tuned, have oem parts, and recommended fluids, I would not even blink an eye at this.
If you're tuned with a bunch of bolt on's, welcome to the rabbit hole.

I have a feeling the coolant thermostat is on its way out. It’s not closing completely for coolant to reach nominal operating temp of 220F in the engine and instead is constantly cycling “cold” coolant thru the engine and radiator. That’s why the coolant temp is 180F and engine oil temp is 210F.

[NSX2M4]

Originally Posted by tjjmx

I have a feeling the coolant thermostat is on its way out. It’s not closing completely for coolant to reach nominal operating temp of 220F in the engine and instead is constantly cycling “cold” coolant thru the engine and radiator. That’s why the coolant temp is 180F and engine oil temp is 210F.

You're in the Bay Area, I lived there for 15 years. Are you sure this isn't just micro climate differences? Fog rolling in VS full sun on these runs?

[tjjmx]

Originally Posted by NSX2M4

You're in the Bay Area, I lived there for 15 years. Are you sure this isn't just micro climate differences? Fog rolling in VS full sun on these runs?

LOL nope, still like this for couple weeks now. Pretty sure the coolant thermostat just can’t close tight.

[ron_s55]

A lot of times in Efficient, my oil is at ~210-212F. Sometimes, at the end of my commute, it will go up to 220F.

I regularly switch from Sport+ to Efficient and back, and I think the DME does more than just use that mode to determine the temp setting.


09 Cooling System.pdf in https://www.e90post.com/forums/showthread.php?t=1032490 for the n54 says
"The control system aims to set a higher cylinder-head temperature (108°C) if the engine control unit determines ECO (economy) mode based on the engine performance.
...
An increase in temperature therefore favors slower fuel consumption in the low load range."

And if it does that on s55, it would explain what I see in Efficient. At 30-40+ mph on the highway, I'll see 212F, but when I hit traffic or the end of my commute, rpms and load are down, so it goes up to 220F.

Just a guess, anyways. I don't mind the lower oil temp.

[M3SQRD]

Originally Posted by jagus

Increase octane, 91 is too low

ACN (Arizona, California, Nevada) 91 ((RON+MON)/2 octane rating) is the highest octane rating sold at most ACN gas stations. It is absolute garbage but it’s already damn expensive that people just live with it.