[C4sF80M3]

So it appears that the stock oil cooler thermostat is no where near the suggested 230F+ that people are stating on the forums. Just finished installing my own oil cooler setup, and with 20 minutes of drive time datalogged, the oil temp stayed in the 195 - 200F range, always decreasing back to 195F at idle.

Any clue where the stock numbers originated from?

[enrita]

http://realoem.com/bmw/showparts.do?...71&hg=11&fg=30

[C4sF80M3]

No it definitely opened. Plus the stock thermostat is more of a restrictor than a fully closed off valve, so oil is always flowing throw it. Plus Stett is offering a 180F oil thermostat which pushes the temps even lower, not that I would recommend that.

Most NA cars will rarely reach 212F unless pushed hard.

Originally Posted by maxnix

Maybe it was too cold for it to open?

You do want your oil above 212° F to boil off condensate once it is fully warmed.

[C4sF80M3]

Am I missing something? Is this supposed to state oil thermostat opening?

Originally Posted by enrita

http://realoem.com/bmw/showparts.do?...71&hg=11&fg=30

[C4sF80M3]

Oil temps usually are 200F are less for most cars.

[anerbe]

Oil is rated at an operating temperature of 100C (212F). Oil has been designed to operate at this condition. Although its' nice to operate at cooler conditions to bring down intake temps (more power), a more complete combustion occurs in a higher temp engine. You'll want a oil cooler that keeps you at safe temperature (around the midway point to 20 deg over ) at the hardest driving conditions and at least 212 in your normal operating conditions. Otherwise I would think that lower operating temperatures will be similar to those who drive short distances and never warm up their engines completely - carbon and sludge buildup (i.e. milky residue under the oil cap). This is water that has never evaporated in the engine.

My wife commutes a few miles every day and rarely brings up her vehicle to operating temp. After I found a lot of sludge on the oil cap and the upper block, I change the oil with synthetic every 3000 miles and try to do WOT runs and high RPM driving to heat up the oil whenever I can.

[C4sF80M3]

That is partially accurate. However, this engine is regulated by water temp not oil temp as most engines are. Oil temp can effect overall combustion, but the reality is the cylinders and heads are water jacketed, not oil jacketed. Proper combustion is set by making the water thermostat a certain temp. Oil is only used for lubrication, and to pull the extreme heat away from the surface of the piston. Most cars will never see oil temps anywhere near what our cars run with the stock oil cooler.

Keep in mind I didn't change anything from stock other than the oil cooler and lines. The stock thermostat is still in play here.

Originally Posted by anerbe

^ this. Oil is rated at an operating temperature of 100C (212F). Oil has been designed to operate at this condition. Although its' nice to operate at cooler conditions to bring down intake temps (more power), a more complete combustion occurs in a higher temp engine. You'll want a oil cooler that keeps you at safe temperature (around the midway point to 20 deg over ) at the hardest driving conditions and at least 212 in your normal operating conditions. Otherwise I would think that lower operating temperatures will be similar to those who drive short distances and never warm up their engines completely - carbon and sludge buildup (i.e. milky residue under the oil cap). This is water that has never evaporated in the engine.

My wife commutes a few miles every day and rarely brings up her vehicle to operating temp. After I found a lot of sludge on the oil cap and the upper block, I change the oil with synthetic every 3000 miles and try to do WOT runs and high RPM driving to heat up the oil whenever I can.

[C4sF80M3]

Also keep in mind those are cruise temps only. With hard back to pulls the temps peaked at 224F.

So really the oil is kept in the ideal range. I'm only asking why does everyone say the stock oil thermostat is set to 230F? Clearly it isn't.

11 minutes of hard driving. No track time just yet. At least not until February.

[C4sF80M3]

Yes! Water coolant! Not OIL!

For proper combustion most cars run water temps in the 180 - 220F. 220 being on the high side of course, but the higher temps help with emissions.

Originally Posted by maxnix

Most modern engines have pressurized coolant temperatures of 195° F to 210° F incoming to the radiators. I think it is safe to presume that at certain places, especially in the head, spot temperatures are well above that average.

[C4sF80M3]

Never said that coolant lubricates the valve train. I said that coolant is used to regulate proper combustion not oil.

Originally Posted by maxnix

So do you really think coolant is cooling and lubricating the valve train?

[enrita]

Originally Posted by c4s335i

Am I missing something? Is this supposed to state oil thermostat opening?

If you look at the thermostat it states 110 CEL which is 230 F . thats when the thermostat opens.

[C4sF80M3]

Wow. The valve train isn't "cooled" so much as it is lubricated to keep the bearings from overheating from friction. The oil never touches the valve face, only the valve stem, and isn't meant to cool the valve face either. And it only is on the valve stem so that it can "lubricate" the valve seals, again to reduce friction. Pretty basic idea here. I've built a few race engines, and you'll never find anyone one who builds engines talking about oil regulating cylinder temps. Oil only needs to operate within a given range to make sure that it reaches desired viscosity on the low end, and doesn't break down on the upper end. Granted you don't want it running really high for no reason either. That obviously can heat soak the engine.

Originally Posted by maxnix

The question is, what is cooling the valve train which valves are transferring the heat directly from the combustion chamber to the lubricant?

Nice dodge, not!

[C4sF80M3]

Interesting. Never seen temperature stated as "CEL", just C or Celsius.

Regardless... Obviously moving to a bigger oil cooler lowers normal oil temp without swapping to a lower temp thermostat.

Originally Posted by enrita

If you look at the thermostat it states 110 CEL which is 230 F . thats when the thermostat opens.

[vasillalov]

Oil cooling is essential for cooling and lubricating the pistons. Why else do you think the N54 and almost all turbocharged engines have oil squirters.

Yes, the cylinders are water jacketed but the pistons are oil cooled.

I agree with the fact that oil temperatures must be kept as close to recommended specs as possible. That being said, I have NEVER seen the oil temps go higher than 240F and this includes driving through traffic gridlocks in downtown Chicago in 90F+ summer days.

[C4sF80M3]

It's pretty simple.... Oil is a lubricant, but oil squirters are used to cool the piston crowns to help eliminate hot spots on the surface of the pistons and prevent detonation. Turbo engines can see EGT's in excess of 1500F, which BTW is the melting point for Aluminum. Using oil squirters also affects the design and tolerance that is required when creating pistons. Water coolant regulates the engine/combustion temperature. High oil temps affects the oils capabilities of extracting heat from the surface of the piston. So know one here is arguing that high oil temps are bad, and that oil isn't cooling the pistons.

None of this has anything to do with my oil temps lowering by just changing the oil cooler, and not changing the thermostat.

And 240F street driving is normal for stock. But the stock cooler will NOT hold up under racing conditions. Oil temps will run in the 260 - 300 range easily, especially for those of us running much higher boost.

Originally Posted by vasillalov

Oil cooling is essential for cooling and lubricating the pistons. Why else do you think the N54 and almost all turbocharged engines have oil squirters.

Yes, the cylinders are water jacketed but the pistons are oil cooled.

I agree with the fact that oil temperatures must be kept as close to recommended specs as possible. That being said, I have NEVER seen the oil temps go higher than 240F and this includes driving through traffic gridlocks in downtown Chicago in 90F+ summer days.

[vasillalov]

Right. I agree.

So what it would seem logical is to keep the OEM oil thermostat and simply add oil cooling capacity by having larger aftermarket oil cooler. That way:

* The engine oil gets to reach the desired operating temps so that any water vapors are burned out
* You have added cooling capacity so that the oil temps do not go over 250F under racing conditions.

Does that seem logical?

[C4sF80M3]

Agreed. Kinda why I started the thread!

BTW... The setup I'm running uses 1 quart of oil, that's oil cooler plus lines.

Originally Posted by vasillalov

Right. I agree.

So what it would seem logical is to keep the OEM oil thermostat and simply add oil cooling capacity by having larger aftermarket oil cooler. That way:

* The engine oil gets to reach the desired operating temps so that any water vapors are burned out
* You have added cooling capacity so that the oil temps do not go over 250F under racing conditions.

Does that seem logical?

[mycoupe]

The water jackets run though the block and the head, using the coolant to cool any and all components of the engine through thermal dynamic properties(heat ALWAYS moves to the colder substance/object). Oil is used to lubricate parts and keep temperatures down by reducing friction. Thermal dynamics happen here as well, hence the oil cooler. SO...the oil and water are used for cooling, while the oil also lubricates vital internal engine components. Therefore, both are going to play a roll in stabilizing engine temps and aid in proper temps for optimal combustion along with the spark, afr and timing.

Can we all just agree on this basic crap and move on to the more important stuff now please?

[taylors335]

Originally Posted by c4s335i

Also keep in mind those are cruise temps only. With hard back to pulls the temps peaked at 224F.

So really the oil is kept in the ideal range. I'm only asking why does everyone say the stock oil thermostat is set to 230F? Clearly it isn't.

11 minutes of hard driving. No track time just yet. At least not until February.

i agree with you the cooler i did i pulled the t-stat out and it says 110 deree on the t-stat itself , i removed mine so i have constant circulation through the coolers and my car will reach temp very quick

[anerbe]

Originally Posted by c4s335i

Agreed. Kinda why I started the thread!

BTW... The setup I'm running uses 1 quart of oil, that's oil cooler plus lines.

So you agree that oil does also regulate engine temp?

Our concern was not on adding the aftermarket oil cooler for a vehicle that will see harder use. I too do not prefer the oil temps reaching past 230.

Our only concern was having the normal operating temp drop 40 degrees lower than vehicle design parameters, 3 ticks away from the lowest reading point. The 212F burning condensate is basic thermodynamics. You will need to drive the car harder to reach these temps, but I have no doubt you'll do it.

However, You should know that engine oil has a optimum operating RANGE, not simply lower is better. Dropping down your oil temps in daily driving will effect the viscosity of the oil to a continuous "almost warmed up" state. The engine itself will probably have no issues with the temp (besides needing to occasionally run the car hard), but I don't know the long term effects on the turbos having cooler oil (higher viscosity) running through them all the time. The bearings in the turbos can't have a viscosity too high. Again, I'm not saying your lower temps are "bad", but the effects on running 40 deg cooler are unknown. Personally, I try not to run the car hard until the oil temp stabilizes, which is normally around 220. Changing anything close to the edge of operating range always makes me a bit uneasy.

If you said your normal driving temps are the same (which should be fixed by your oil thermostat), but you've greatly decreased the peak temps you see during hard driving, I'd say great! However, the drop in oil temp makes me wonder on the effectiveness of the thermostat.

So I guess to be on the 100% safe side, drive the car hard all the time!