Unusual oil temperatures and oil behavior - 08 S65 142K miles / VAC / CSF Rad

[tdott]

Originally Posted by amrazM

It seems too unlikely, the oil thermostat is a mechanically controlled part. Depending how mechanically inclined you are it may be possible to remove the housing and test the thermostat as the whole housing is nearly $400

https://www.getbmwparts.com/oem-part...ly-11427841525

Even though they are mechanical, I've seen them fail, in some cases either not opening fully or not closing fully. But yes an oil tstat issue is pretty rare but I wouldn't say outside the realm of possibility.

[Ervin87]

Your coolant thermostat is not an issue. The S65 thermostat is open without a coolant block off. The ECU reads how quickly engine gets up to operating temperature, and will throw a code if those parameters are not met. A bad thermostat would essentially take longer to warm up and throw a code. Your issue is the opposite. Your oil cooler is pitted, but If cold after reaching operating temperature, take a look at the oil thermostat. This thermostat is closed when the engine is cold so that the oil warms up quicker. Yours may not be opening enough to keep the temps down.

[jeremyuhh]

Update 03/30

Still waiting on parts to come in before i start any of the replacing. So far the only thing ive done was clean and straighten my oil cooler and AC condenser.

Ive been driving the car here and there and surprisingly have not reached the middle of 210F and the dot. Though it is still going passed 210F its doing a better job cooling down, street or highway driving.

Last night, i drove the car pretty hard for the first time and temps did well. Still passed 210F but seemed normal for the type of driving i was doing. 58F outside temp, empty freeways, just under 4k rpm. When took it easy it cooled down as it should but stayed just above 210F and i could see the needle fluctuate, not a ton but enough for me to notice it isnt staying still while looking down when driving. Maybe its just a bad temp sensor ?

At a stop, red light, or stand still, temps still rise but again not passed the midpoint of 210F and the dot. Just above or on the "0" of 210. Which makes me think my fan isnt cooling when it should be.

As far as oil cooler, ive checked 3 times after 40mile highway drives and its still stone cold. Which makes me believe my oil thermostat is not fully opening as Ervin87 and others have suggested.

In conclusion, im going to change my coolant temp sensor, the sensors wire, pull off my OFH and inspect the oil thermo and possibly replace it with a diverter valve.

[BPMSport]

Change the thermostat/radiator. The oil is creeping up because the coolant temps are higher than they should be.

[jeremyuhh]

Originally Posted by BPMSport

Change the thermostat/radiator. The oil is creeping up because the coolant temps are higher than they should be.

So ditch the CSF rad ? Was already thinking about replacing the thermostat but others said it would throw a code before going bad. Was replaced 3 years ago with an oe bmw thermostat. Guessing 45-50k miles on it. Was done by previous owner.

[BPMSport]

Originally Posted by jeremyuhh

So ditch the CSF rad ? Was already thinking about replacing the thermostat but others said it would throw a code before going bad. Was replaced 3 years ago with an oe bmw thermostat. Guessing 45-50k miles on it. Was done by previous owner.

Thermostat can be faulty without triggering a code. We battled a car last week that had cooler oil temps (190), and this was because the thermostat was stuck open. Coolant temp was way under threshold so it wouldn't pass oxygen sensor readiness. It would reach about 178F eventually but at speed it would quickly fall to the 150F range. After replacing the thermostat, oil temp went into the 200-210 range and coolant temp was back up to 180-200F.

I'd replace that first or at least monitor the relationship/correlation of oil to coolant temp for further analysis.

[jeremyuhh]

Originally Posted by BPMSport

It will absolutely not throw a code unless it's WAY off. We battled a car last week that had beautiful oil temps (190), and it was because the thermostat was stuck open. No codes and coolant temp was way under threshold so it would pass oxygen sensor readiness. After replacing the thermostat oil temp went to 210 and all was good. I'd replace that first

Copy. I have all the parts, just came in today actually, so I'll go ahead and do it all. Thanks

[Helmsman]

Originally Posted by jeremyuhh

So ditch the CSF rad ? Was already thinking about replacing the thermostat but others said it would throw a code before going bad. Was replaced 3 years ago with an oe bmw thermostat. Guessing 45-50k miles on it. Was done by previous owner.

Seems to be a typical life time. Replaced mine (coolant tstat) at 49k miles, probably went bust a few k miles prior.
No codes.

[jeremyuhh]

Updated 04/03:

Drove a total of 120 free way miles. Mostly free flowing, 58-60F outside temperature with some patches of traffic and my oil temp was glued to this position


Seems acceptable but still on the high side compared to what im used to. But around 117 miles, as i approached my exit, i noticed my temps began to climb again, in between 210F and the dot. The only real difference is that those last 3 miles are all up hill and downhill. No AC and this time driving faster than normal when the lanes were empty.

Another note: i also just re-installed my test pies and installed a AA exhaust plus switched to a catless tune. But I dont think that contributes to my oil temps though, will it ?

[slcook54]

Did you replace coolant temp sensor and pigtail yet?

[jeremyuhh]

Originally Posted by slcook54

Did you replace coolant temp sensor and pigtail yet?

Nope. Have everything except my macht schnell pulley. Just waiting on that so I knock it all out at once.

[wrk.eat.drive.rpt]

Originally Posted by jeremyuhh

Nope. Have everything except my macht schnell pulley. Just waiting on that so I knock it all out at once.

Just checking in on progress !

[BPMSport]

Originally Posted by jeremyuhh

Updated 04/03:

Drove a total of 120 free way miles. Mostly free flowing, 58-60F outside temperature with some patches of traffic and my oil temp was glued to this position


Seems acceptable but still on the high side compared to what im used to. But around 117 miles, as i approached my exit, i noticed my temps began to climb again, in between 210F and the dot. The only real difference is that those last 3 miles are all up hill and downhill. No AC and this time driving faster than normal when the lanes were empty.

Another note: i also just re-installed my test pies and installed a AA exhaust plus switched to a catless tune. But I dont think that contributes to my oil temps though, will it ?

This is a completely normal temperature for maintaining that RPM. Again, posting these temps without also looking at coolant temperature is a completely futile exercise. I suggest you pull coolant temp through the clusters secret menu so you can monitor both at the same time, otherwise any conclusions you draw are 100% invalid.

[SAMM3Y]

Not sure if it helps but my oil temp lives there, about 215-219 and coolant temp is 195f, radiator temp is 165f.

[jeremyuhh]

Originally Posted by BPMSport

This is a completely normal temperature for maintaining that RPM. Again, posting these temps without also looking at coolant temperature is a completely futile exercise. I suggest you pull coolant temp through the clusters secret menu so you can monitor both at the same time, otherwise any conclusions you draw are 100% invalid.

Originally Posted by SAMM3Y

Not sure if it helps but my oil temp lives there, about 215-219 and coolant temp is 195f, radiator temp is 165f.

Will do.

Last time i checked my coolant temp through Carly it read this. Same speed/rpm and no traffic (this was before I adjusted my Speedo digital reading)

[Helmsman]

Originally Posted by jeremyuhh

Will do.

Last time i checked my coolant temp through Carly it read this. Same speed/rpm and no traffic (this was before I adjusted my Speedo digital reading)

Believe you've picked the wrong parameter mate. Bit odd but the coolant temp is "engine temp", while the engine (oil) temp is "output value for motoroeltemp". See attached. The "coolant temp" parameter clearly doesn't work the way one would expect, while the "engine temp" def show coolant.

Edit: lol, just realized you obviously measure in F, the high numver got me confused. Yeah, like Mike day further down, coolant need and should be around 80C as long as youre driving/have proper airflow.

[brettcp]

Definitely replace the coolant temp sensor. I did my thermostat and coolant temp sensor both at once (at 110k miles) and immediately noticed a much more stable temp reading.. mine is almost always dead center, maybe a hair above if its a hot day.

[NeverL8]

Originally Posted by brettcp

Definitely replace the coolant temp sensor. I did my thermostat and coolant temp sensor both at once (at 110k miles) and immediately noticed a much more stable temp reading.. mine is almost always dead center, maybe a hair above if its a hot day.

That was my first thought in the beginning. Easy fix under $50

[BPMSport]

Coolant temp sensor is likely fine. 205F coolant temp is exactly why you are seeing the oil temps you are - as I previously suspected.

The M3 has a 79C thermostat = 174F. You're pushing 97C.

If you want to bring your oil temps down, you need to solve cooling system or airflow issues, and also ensure that the electronic fans are operating as designed.

Once your coolant temp is 79-85C, you'll see the needle nearly center.

[bmwm3s65]

Originally Posted by BPMSport

This is a completely normal temperature for maintaining that RPM. Again, posting these temps without also looking at coolant temperature is a completely futile exercise. I suggest you pull coolant temp through the clusters secret menu so you can monitor both at the same time, otherwise any conclusions you draw are 100% invalid.

I have a bmw remanned engine essentially brand new, i just took it on highway for the first time this past weekend when i drove to the dragon and i had the same exact temps at the same speeds. appears normal to me.

[RomanK]

Take a look at this - https://www.drive2.ru/l/452185702868714578/ It is my post. The problem was in oil thermostat. Just try to touch oil cooler after the car is warm. If it is cold - this is a reason for sure.

[tdott]

Originally Posted by RomanK

Take a look at this - https://www.drive2.ru/l/452185702868714578/ It is my post. The problem was in oil thermostat. Just try to touch oil cooler after the car is warm. If it is cold - this is a reason for sure.

A little hard to understand what you did.

Were you able to change just the oil thermostat or did you use one from another housing? Where did you get the part from? I don't believe BMW sells this part separately.