Different oil temperatures

The Anti-wear agents in oil do not start to work untill 200dF-210dF (ZDDP)
Secondly, the viscosity of the oils only where the manufacture intended when the <factory grade/weight> oil is in the window from 190-225.
Water will not completely boil out of the oil until it gets to 215dF.
Engines that run with the water above 200dF and the oil above 215dF last longer.
Hotter oil is thinner (in that it pumps easier) and flows faster through the engine which allows it to can carry more heat from journal bearings.

 

Without taking the time to actually check, my first inclination is to think that a lot depends on where you measure the oil temperature. For example, one car may measure the temp as it exits the scavenge pump or just before oil enters the oil cooler and another may measure it as it exits the cooler or perhaps as it leaves the oil tank. The two car brands could have nearly identical oil systems and nearly identical oil temperatures throughout the engine, yet display quite different temperatures on the cockpit gauge.

I know for a fact that this sort of perceived difference is common with different aircraft types/brands because one engine designer may feel it's important to know the highest oil temperature in the oiling system and another may consider it more important to monitor the temperature of the oil being fed to the engine.

 

The precision of OEM dashboard instruments is always suspect. The differences might not be as great as you think.

 

My explanation is: higher temperature -> lower viscosity -> less friction -> less comsumption. The people are only looking at mpg (especially her in Europe). The risk is of course the the motor will not last longer than 100000km. Who cares. I read a lot about the TSI motors of VW which have a low comsumption, but break down quite early.

 

A man with two watches never know what time it is . . . .

Two cars, two oil temp gauges . . . I'd bet the keys to a 275 that the gauges do not agree.

 

My wife's Porsche Cayenne diesel runs 220-235 deg at freeway speeds. I thought this to be high, however the Porsche dealer says it is within factory operating specs. Of course, my experience with Porsche dealers is they say that for just about any concern a new car owner has.
My 365 GTC/4 used to run cold oil temp all the time. Turns out the oil cooler bypass/thermostat was stuck open. After dismantling, cleaning and inspecting, it works fine and oil temp sits around 200-210 deg under normal operating conditions.

 

Because you are not driving fast enough - ZING!

Seriously, the F oil cooling systems are designed to hold very high speeds for very long time. If you ran the BMW near WOT for an extended period, it would probably overheat -- just like a big displacement muscle car with only 5 qts of oil in the sump and no oil cooler -- it can do ~150 mph, but not for very long.

I agree with NoSpeedLimit that manufacturers got pushed to using thinner oil to get a better MPG rating. Understand the "thinner = more oil gets there sooner/gives better cooling" argument, but the load capacity/film thickness of a journal bearing goes down with viscosity IIRC -- so there has to be some sort of trade-off/optimum in there...

 

Concerning oil temperatures: even 150°C (300°F) for a good oil is nothing. The critical point for the oil is the area close to the pistons. Oil can reach temperatures of 300°C (570°F) in that part of a motor.
What is the temperaure of the motor oil? It depends where you measure it. Does your BMW has an oil cooler? I think Ferraris have oil coolers, don't they? I just checked some forums and according to some guys 110-120°C is the normal oil temperature for a BMW. Porsches tend to have somewhat lower oil temperatures around 100°C.
For me the 80°C oil temperatures of your Ferraris seem to be on the cold side.

 

Yes you get the same effect while drivnig like an adult, but you lose the ability to run the snot out of the car as the oil will lose too much viscosity and metal to metal contact may happen.

 

Optimizing oil temperature to a specific target value is generally not a major design driver ---- rather it is a consequence of the rest of the design.

Your BMW engine is much smaller (less total thermal mass) than that of your 512 & 575, so it will run hotter. And, unless it is dry-sumped (with a large capacity external reservoir) it does not have as much oil available for absorbing the heat. Also, the turbos are likely oil fed / cooled ---- this will put a lot of extra heat into the oil and result in a higher operating temperature. Oil coolers, etc. can be added if, during testing and development, the temps are making excursions into the range where the performance of the oil is being compromised or if critical components are exceeding their allowable max design envelop temps. But, there are also packaging constraints and build / design cost considerations to be taken into account.

During testing, if it is concluded that the engine meets its desired targets for performance and reliability, whatever the resultant oil temps are.....so be it ---- so long as they are within acceptable limits.

Furthermore, the balance between cooling capacity from the coolant vs. cooling from the oil is different for different engines. The block and heads act as heat exchangers between the oil and the coolant --- so they can influence each others temps somewhat. Those that rely more on the coolant scheme will generally have lower operating oil temperatures, and vice versa. Again, this is more of an overall consequence (cause and effect), rather than an intentional oil temperature design target.

My point is that neither BMW nor Ferrari is likely designing their engines to run at "X" oil temperature. Instead, they are ending up running at "Y" oil temperature as an acceptable result of the rest of the design.

As a side note ---

Thermal management / control is probably one of Ferrari's weakest design areas ---- they have always had various problems with various things resulting from critical temperature effects (usually too hot). So, I would not make the assumption that whatever the "normal operating" oil temp is for any Ferrari engine, that it is necessarily the ideal design point (even for their own engine ), either.

After all, Ferrari does not strive / has not ever claimed to design their engines for 100,000+ miles life .

 

Anything in the 180 to 220 deg F range would be considered normal design. Designs at the low end tend to favor all out performance from lower piston temps from oil cooling and general cooler temps. Designs that favor the higher temps put more of a premium on getting any condensation out of the water and possibly part fuel throttle efficiency. Basically they are are optimized for their intended customers. But frankly there is not a lot of difference in the two.

Cheers Jim

 

You got it in a nutshell --- you are a quick study !

Sorry about the wife...... but, yeah, damned if sometimes they are not actually right about some things

 

My air cooled Harley Deuce runs about 200F +/- 5-10 degrees in normal driving conditions and ambient temps.