Yuille36

No, as both these circuits are separate from one another.

hachiroku

the oil cooler thermostat is on the o-ring that failed on that R63 that had 171 pages on that other site. mine leaked as well and there was a revision to the design over the years. the cover changed and I believe the spring and plunger did as well.

here are some photos from my car.

Yuille36

I don't have a oil leak, just a fluctuating oil temperature reading in the cluster.
But I spoke with my mechanic this morning, and he said he couldn't find any parts for this.
Besides, I would be looking at $4-5K in labor. And I'm just not willing to spend that much, for a issue that isn't critical to the functioning of my engine.
For $4000, I will live with it, and tell my OCD to take a hike But thank you for this information, it was very helpful.

hachiroku

jumping of temps is one thing, but if for any reason oil temps are reading much higher than normal the computer will cut power or hit limp mode.

if you know anyone with HP Tuners, you can datalog your car and send it my way. I can let you know if your oil temps are out fo the norm for an M156.

Yuille36

My oil temperature variance are not extreme, just a few degrees + or - but offering to help me is much appreciated.

Yuille36

Had a long conversation with my tech today, after dropping off my X5M to have its spark plugs changed along with it serpentine belt.

He thinks that my temperature variances is due to the oil thermostat opening and closing thereby causing the variances.

And when he explained it, it made perfect sense to me, and he also described the procedure and cost to replacing it.

Given the cost, I can and will live with it. 😁

jpman

Good approach as I can’t see anything wrong with it if the thermostat is stuck open. I don’t really care about it to be honest, and I won’t repair it for the cost/trouble to replace it.

Yuille36

If, I was so inclined to replace it, this would be my cost expensive repair to date. The minor annoyance is outweigh, by the shear cost.

benzokirk

I probably should leave well enough alone, but I've been gone for awhile and returning tonight to see this thread which interests me because my car has done the same thing from the first day I owned it. I've been told that it's normal and I would agree with that. I also wanted to point out that, unless I missed something above, what you're describing isn't a true "fluctuation" unless (as jpman described) the oil temperature gets cooler, by any degree, and then gets hotter again. As long as it's getting incrementally hotter, it's not a fluctuation just because it jumps a couple of degrees after reporting single degrees at a time, if that makes sense. I'm currently sitting at 166k+ miles with the car doing the same thing as yours, if that helps put your mind at ease, at all.

hachiroku

mine has only done that once ever now that i think about it...it very well may be the thermostat jittering with its movement. i'm at 160k now.

Dublinoh

I think I’m having a similar issue with my E63 07 141k miles. My car has always read 101 oil temperature. I thought that was normal. But now I see 103 then 105 then 107 sometimes higher, then it will drop to 103, 102 maybe 101 and stay there. I noticed this recently while trying to track down another issue. Water temperature is steady. Car is running very smooth and strong. I haven't heard the fan mentioned above. I suspected there was an oil thermostat and this is the first thread I’ve found that mentions it. Do you think it would be worth replacing the temp sensor? Is it an easy diy? Thanks

Yuille36

Why not, but this sensor is a pain to get at, with very little clearance.

nileswloo

must have good oil filters

Dublinoh

I agree, this will be my take away as well. Unless the presumed inaccurate temperature readings trigger limp mode or other issues I’ll look the other way. Good post with some good information.

Yuille36

Definitely wait until you require other repairs in that general vicinity. I had my upper/lower oil pan gaskets, engine mounts and transmission mounts done, and replaced the oil temp sensor while in there.

W126AMG

My "normal" oil temp in my 09 E63 is 102 C (Atlanta). I have seen it get to 113-115 briefly in stop and go traffic, but always returns to 102. Spirited driving in Manual will drive up the temp to 105-107, but always returns to 102 eventually.

Yuille36

My oil temp are steady now, no more wild fluctuations.

hachiroku

what did you do? replace your oil temp sensor?

Yuille36

Yes, I replaced it. And my temps have been running steady.