[Lehan]

BMW F/G chassis oil level sensor and overfill for track use guide.

Note: This is not a recommendation to overfill, but rather to help people who overfill their engine for track use to measure oil level accurately. This article will explain the oil level sensor of the F/G chassis, and how you may be able to overfill your track Car. All information will refer only to the F/G chassis. Overfilling 500ml to 1000ml is usually fine for the BMW inline 6; it is a cheap way to prevent oil starvation. Oil starvation is a common issue on the N55 and N54 on track; however, since this guide will only cover F chassis or newer, I will be mainly focusing on the N55.


Important: You do not need to overfill for daily use, and most road tires will not allow you to make high enough G for oil starvation.


I have found that a BMW provides four different lengths of oil level sensors for F/G chassis. All electronically interchangeable but will measure a different maximum/minimum fill.

12617638341 fitting depth: 87mm
+7mm
12618638754 fitting depth: 94mm
+16mm
12618608780 fitting depth: 110mm
+13mm
12618638755 fitting depth: 123mm

There is also a spacer if you want to reach any number in between. However, I am unsure of the exact thickness of the spacer; if anyone has purchased one, I would highly appreciate it if you provided the info below.

11137857266 spacer (looks to be around 5mm on picture)

BMW used the spacer (5mm?) on the M4 S55 GTS/CS in conjunction with a longer sensor(110->123mm) to read an extra 750ml of oil. This has shown that a 8mm longer sensor, will read 750ml extra oil. (1mm ~ 100ml on S55)



Bimmerlink can read the direct oil level.
The following data (may vary on model) is measured on 435i 2014 EWG RWD w/ M Sports oil cooler at operating temp + idle rpm

Raw 74mm (engine off) (maximum possible reading from sensor)

Raw 63mm (shows half on iDrive)
500ml
Raw 69mm (shows full on idrive)
500ml overfill
Raw 74.71mm(Max possible reading)

Taken from this,
Though I have made the mistake of filling to the max reading so I am unsure of the exact number of the final reading. Assuming the oil reading is linear, it should be around a 6mm increase on the N55. Therefore on N55 6mm~500ml. This should be accurate since the S55 sump is wider.

I have ordered the 94mm sensor, 7mm+ (adds ~580ml reading in idrive, + total 1000ml overfill reading via sensor)

I will update the readings on the next oil change as soon as my sensor arrives, where I will also be testing a longer sensor. I will update corresponding oil levels (eg, the amount drained + level before, the amount filled + level after).

[Sorry, English isn't my first language, if there are any typos or grammatical errors, please dm me and I will correct them. For errors on the information I provided, please reply to the thread below, thanks!]

Common sensor model (RWD if xdrive not mentioned)

87mm (12617638341 )
N20
N26
N20 xdrive
N26 xdrive
N55 non-Mpower

94mm (12618638754)
N55 M2
B38 F4x
N63 xdrive(G3x)
S55 (Early magnesium pan?)

110mm (12618608780 )
N55 xdrive
N47xdrive
N63
N63 xdrive
S55 non-GTS/CS (aluminium pan?)

123mm (12618638755 )
B38 F3x
B47
B47 xdrive
B48
B48 xdrive
B57
B57xdrive
B58
B58 xdrive
N63(G3x)
S55 GTS/CS (same pan as early magnesium pan?)
s63


Refrencing

https://www.realoem.com/bmw/enUS/par...&q=12617638341

https://www.realoem.com/bmw/enUS/partxref?q=12618638754

https://www.realoem.com/bmw/enUS/par...780&series=F30

https://www.realoem.com/bmw/enUS/par...&q=12618638755

https://www.autodoc.co.uk/car-parts/oem/12617638341

https://www.autodoc.co.uk/spares-sea...rd=12618638754

https://www.autodoc.co.uk/car-parts/oem/12618608780

https://www.autodoc.co.uk/car-parts/oem/12618638755

https://www.fcpeuro.com/products/bmw...mw-11137857266

https://f30.bimmerpost.com/forums/sh....php?t=1917614

[visionaut]

So if I have the 110mm depth oil level sensor (N55 Xdrive), I could get the 123mm version, giving me an additional 13mm to Full. And since N55 is 500ml/6mm, I could add the sensor and run an extra full liter of oil (1.1ltr) to measure at Full. ??

Neat. So how does the engine like/handle/respond to the extra liter of oil?
(No windage tray, no slosh baffle). With and without Xdrive?

It’s my understanding that Xdrive has less “oiling in left turn” issues than RWD.

[Lehan]

Originally Posted by visionaut

So if I have the 110mm depth oil level sensor (N55 Xdrive), I could get the 123mm version, giving me an additional 13mm to Full. And since N55 is 500ml/6mm, I could add the sensor and run an extra full liter of oil (1.1ltr) to measure at Full. ??

Neat. So how does the engine like/handle/respond to the extra liter of oil?
(No windage tray, no slosh baffle). With and without Xdrive?

It’s my understanding that Xdrive has less “oiling in left turn” issues than RWD.

I have seen some post that indicate the Xdrive have a smaller pan, with the oil level sitting higher and don’t recommend overfill in the xdrive N55. It could even be why the xdrive have a longer oil level sensor to begin with.

Also the oil in left turn issues is pretty much non existent, even in the RWD version. I had my track sessions last Sunday with 500ml over fill and there was no oiling issues. Despite my track has a 140km/h to 50km/h hairpin left turn, and a 160km/h to 100km/h left long.

Unless you track competitively, I wouldn’t worry about it.

[johnung]

Thanks for all your research. I think you just solved a mystery. The most recent oil level sensor installed on my 335ix never reads higher than about 3/4+ full despite measuring carefully the oil used during an oil change.

It’s likely that I was given the incorrect part number for the sensor. Never thought to double check the part number because I never knew that there were others.

I think that I’m on my 4th oil level sensor. They go bad often. They’ll constantly give an error on startup that oil lever is to low and advise to add a quart. Yet when I warm up the engine enough to check oil level it always shows that it is fine. Eventually when it gets to the point when it happens every time that I start the car, I just replace the sensor during my next oil change. Then the new sensor eventually fails the same way.

To add to the discussion, the N55 F3x RWD oil pan is a wide open rectangular box so it’s very susceptible to G-forces with the oil sloshing away from the oil pickup. This typically happens during very specific scenarios. Very high track track speeds with a long sweeping curve can cause. It’s either a left or right curve- I can’t recall which. Also very hard braking such as at the end of a high speed straightaway, can cause it.

The N55 F3x XDrive oilpan is shaped very differently inside. It has a front driveshaft going through it. The inside of an XDrive oilpan acts as a natural baffle so it doesn’t have as many G-force oil starvation issues. See attached photo comparing RWD and XDrive oil pans.

Note: there is a ton posted about oil starvation fixes, oil pan baffles, converting configurations used in other BMW cars, installing rod bearings like VAC Coated bearings that resist oil starvation, etc. So if you have more questions just search for those posts. It’s not worth just rewriting it all here.

[AmuroRay]

Originally Posted by Lehan

BMW F/G chassis oil level sensor and overfill for track use guide.

Note: This is not a recommendation to overfill, but rather to help people who overfill their engine for track use to measure oil level accurately. This article will explain the oil level sensor of the F/G chassis, and how you may be able to overfill your track Car. All information will refer only to the F/G chassis. Overfilling 500ml to 1000ml is usually fine for the BMW inline 6; it is a cheap way to prevent oil starvation. Oil starvation is a common issue on the N55 and N54 on track; however, since this guide will only cover F chassis or newer, I will be mainly focusing on the N55.


Important: You do not need to overfill for daily use, and most road tires will not allow you to make high enough G for oil starvation.


I have found that a BMW provides four different lengths of oil level sensors for F/G chassis. All electronically interchangeable but will measure a different maximum/minimum fill.

12617638341 fitting depth: 87mm
+7mm
12618638754 fitting depth: 94mm
+16mm
12618608780 fitting depth: 110mm
+13mm
12618638755 fitting depth: 123mm

There is also a spacer if you want to reach any number in between. However, I am unsure of the exact thickness of the spacer; if anyone has purchased one, I would highly appreciate it if you provided the info below.

11137857266 spacer (looks to be around 5mm on picture)

BMW used the spacer (5mm?) on the M4 S55 GTS/CS in conjunction with a longer sensor(110->123mm) to read an extra 750ml of oil. This has shown that a 8mm longer sensor, will read 750ml extra oil. (1mm ~ 100ml on S55)



Bimmerlink can read the direct oil level.
The following data (may vary on model) is measured on 435i 2014 EWG RWD w/ M Sports oil cooler at operating temp + idle rpm

Raw 74mm (engine off) (maximum possible reading from sensor)

Raw 63mm (shows half on iDrive)
500ml
Raw 69mm (shows full on idrive)
500ml overfill
Raw 74.71mm(Max possible reading)

Taken from this,
Though I have made the mistake of filling to the max reading so I am unsure of the exact number of the final reading. Assuming the oil reading is linear, it should be around a 6mm increase on the N55. Therefore on N55 6mm~500ml. This should be accurate since the S55 sump is wider.

I have ordered the 94mm sensor, 7mm+ (adds ~580ml reading in idrive, + total 1000ml overfill reading via sensor)

I will update the readings on the next oil change as soon as my sensor arrives, where I will also be testing a longer sensor. I will update corresponding oil levels (eg, the amount drained + level before, the amount filled + level after).

[Sorry, English isn't my first language, if there are any typos or grammatical errors, please dm me and I will correct them. For errors on the information I provided, please reply to the thread below, thanks!]

Common sensor model (RWD if xdrive not mentioned)

87mm (12617638341 )
N20
N26
N20 xdrive
N26 xdrive
N55 non-Mpower

94mm (12618638754)
N55 M2
B38 F4x
N63 xdrive(G3x)
S55 (Early magnesium pan?)

110mm (12618608780 )
N55 xdrive
N47xdrive
N63
N63 xdrive
S55 non-GTS/CS (aluminium pan?)

123mm (12618638755 )
B38 F3x
B47
B47 xdrive
B48
B48 xdrive
B57
B57xdrive
B58
B58 xdrive
N63(G3x)
S55 GTS/CS (same pan as early magnesium pan?)
s63


Refrencing

https://www.realoem.com/bmw/enUS/par...&q=12617638341

https://www.realoem.com/bmw/enUS/partxref?q=12618638754

https://www.realoem.com/bmw/enUS/par...780&series=F30

https://www.realoem.com/bmw/enUS/par...&q=12618638755

https://www.autodoc.co.uk/car-parts/oem/12617638341

https://www.autodoc.co.uk/spares-sea...rd=12618638754

https://www.autodoc.co.uk/car-parts/oem/12618608780

https://www.autodoc.co.uk/car-parts/oem/12618638755

https://www.fcpeuro.com/products/bmw...mw-11137857266

https://f30.bimmerpost.com/forums/sh....php?t=1917614

Sorry, I don't follow - I have an M235i, which sensor would I use to do the pan overfill of 7.5L? Do I need the spacer?

[Lehan]

Originally Posted by AmuroRay

Sorry, I don't follow - I have an M235i, which sensor would I use to do the pan overfill of 7.5L? Do I need the spacer?

Hi, we should share the same oiling system. I have a 435i EWG.
I believe we have:
12617638341 fitting depth: 87mm
I ordered:
12618638754 fitting depth: 94mm
I believe it should allow for around 580ml extra reading in iDrive, you could get an extra 500ml of reading on top from reading the raw oil level via OBD2.

I will update you on the exact numbers I get once I change my oil and replace my sensor.

[Lehan]

Here is the 12618638754 fitting depth: 94mm.
Looks like the 94mm is from the top of the base to the bottom of the white tip.

[Lehan]

Update! Because the side wall angle of the oil pan, N55 F chassis RWD model longer oil sensor is about 2mm too long. The GTS spacer kit will required for this mod.

[Jkosmic81]

Originally Posted by Lehan

Hi, we should share the same oiling system. I have a 435i EWG.
I believe we have:
12617638341 fitting depth: 87mm
I ordered:
12618638754 fitting depth: 94mm
I believe it should allow for around 580ml extra reading in iDrive, you could get an extra 500ml of reading on top from reading the raw oil level via OBD2.

I will update you on the exact numbers I get once I change my oil and replace my sensor.

So in total you're physically adding 1.8L over the min from Idrive by using the 94mm sensor? Thinking about doing this.

[semper]

Any further updates? did it work with GTS sensor? thanks