Normal Oil and Water temps or is my thermostat failed open?

[interlagosbluee92]

Hi guys, I have an 08 6mt m3 that I got a month ago. Previous owner showed me a fault code for thermostat he had last summer but cleared it and it never came back.

Last night I went on a drive in 3C (37.4F) weather, went to a drive through, got to normal oil operating temp (95C–100C / 203F–212F), and checked my live data through my scan tool and coolant temps were around 84C (183F).

I then went for a spirited drive on the highway and as soon as I started driving (revving it out to 6000-8000rpm) and going over 140kph (85mph+) my oil temps dropped to 75–80C (167F–176F), and never climbed back to normal oil temps all the way home.

Mind you the ambient temp was only 3C (37.4F). Is this what you guys experience driving in the winter/fall?

I have yet to drive this car in the summer in traffic so I've never actually hit >100C (>212F) which I wanted to do to burn off moisture in the oil. Mind you im coming from a 3 series e92 so im used to 120C+ (248F+) oil operating temps.

[drwankel]

Maybe. Those temperatures do indeed seem too low even for 37F.

Have you driven the car since this incident? I'd be wondering what temps it hits during normal warmup on the next start.

If the thermostat has indeed failed open, it should be very apparent during warmup on the next drive. The car will take quite a lot longer to warm up, and possibly never hit temp. Your previous startup description seems like normal operation.

[interlagosbluee92]

Originally Posted by drwankel

Maybe. Those temperatures do indeed seem too low even for 37F.

Have you driven the car since this incident? I'd be wondering what temps it hits during normal warmup on the next start.

If the thermostat has indeed failed open, it should be very apparent during warmup on the next drive. The car will take quite a lot longer to warm up, and possibly never hit temp. Your previous startup description seems like normal operation.

Everytime ive driven it it's never hit 100C (middle of oil temp gauge).

It gets to 50C (1/4th) pretty quickly though, like within 5 minutes or so.

[steveff4]

I would be suspect of the thermostat. I replaced mine without too much trouble. After doing so, the car oil temp came up quicker and my gas mileage improved.