whoover

My point is that engine oil temp is affected by transmission temperature via conduction. Whether you agree or not, I hope you understand.

Ingenieur

I would say tranny oil temp is affected by engine temp
The heat flow or transfer would be from engine to tranny since it is a larger mass and hotter
Imo

The engine also has a an oil cooler bypass in the block that bypasses when the oil is too cool (warm up basically) and at low pressure (idle primarily)

If the oil temp was not controlled on a below zero day the oil temp would be too low
It seems to be the same hot or cold with only the response time changing?

whoover

Most people who have had overtemp problems at the track have reported it was transmission oil temperatures causing the tranny to go into limp mode. But if you're sure that the engine is always hotter, they must be wrong. Another mystery solved.

Ingenieur

I have no doubt the tranny temp causes the limp mode
I don't agree it is over heated by the engine but rather its own construction

The 2 trannies only differ
TC vs MCT
Control software

The mct has less slip so it gets hotter, ie transfers more energy
It is also spinning in a sump partially immersed
TC no real mechanical connection, fluid coupled
More of the heat is conveyed ot of the system
MCT more heat is retained in the components

It is my understanding it is only used to start off
The the tranny clutch bands do the rest, just like the TC version

The TC cars seem to have less tranny over heating issues
If it was the engine heat and not the mct wouldn't they suffer the same?
With a tc fluid temp is not as critical
With a wet pack if the fuid gets too hot the friction material is destroyed
Hence the limp or safety mode

It's interesting
Sealed wet clutch packs are used on a lot of heavy equipment
Mining, excavating, etc
Usually for BRAKING
for power transmmission TC's are generally used

Questions
Is the wet pack fluid the same circuit as the tranny?
Or is it seperate?
Does the mct take the same volume of fluid as the tc version?

Starky_

Just for reference if anyone is interested.

Ambient temp today was around 26-27C. Cruising in C mode for roughly an hour or so and ~20minutes in stop&go traffic. Saw oil temp reach 111C but dropped down to 102-107C shortly after.

Will try to update when I can throw the car around a bit more in manual mode, tomorrows weather is looking pretty sweet .

Oh, this is on a preface lift 63.

whoover

Watched the temp on run up my hill, in second, the whole way. 5,000+ on the straights, whatever it took on the hairpins.

Started at 221, where I had been in town. It rose to 235 on hill and stayed there until last 1/4 mile, when it jumped to 247. Interestingly, the road gets steeper there. The grade for that final 1/4 mile is 20%. It's documented as the steepest road in the county, on bike enthusiast websites. Obviously, the engine is delivering more HP to maintain speed on that stretch. Once the oil temp gets to 247, it stays there for quite some time, even with the fan going.

On my recent trip to LA, I watched the oil temp on the Grapevine, a 40 mile stretch of I-5 that rises 4,000 feet from the Central Valley through the Tehachapi Mountains. Even at 90 MPH, the temp never got over 220. A little bit of 20% grade is a lot harder than a lot of 6% grade for the engine.

If I lived 1/4 mile lower on my road I'd probably never have seen 235+.

I've never seen coolant temp over 197.

Ingenieur

20% is 11 deg and required 20% more torque than level
6% is 3.5 deg and required 6% more
Basically the sine of the angle
But must be considered
20% at 30 mph is the same work as 57 on the 6%
Assume gearing is constant
If in a lower gear at 30 you have more torque multiplication
Without knowing the velocity it's difficult to say which is a greater load

So chances are the 90 mph takes more power but you have more cooling
The variables (assuming the physical parameters are constant, cooler area, etc)

Oil pump volume
Oil temp in
Air flow volume
Air temp in

The faster you go the better it cools even though the engine might be working harder
Temp rises in stop- go and no load
Temp drops when you start moving but more load

I pulled mine up a steep grade today no issues
2 run away truck ramps
2 mandatory stops
Max speed 10 mph for trucks
On the downhill side

I'll have to see if I can find the grade
But with engine hot (ran for at least 30 min)
And FLYING up at >100 and accelersting to redline
Started at 210 may have hit 225 max
OAT 80 f

Car ran like a scalded ape lol

If I saw 250 I'd be concerned
Not because of the ABS temp
But because of the change from what I am seeing

whoover

I'm not concerned. As has been reported many times (including post #22 in this thread) post-facelift cars run 15-25 degrees hotter. Also, P31 putting out max power will exacerbate problem.

Vlinkz

I just happen to find this thread while searching so I'm just wondering since the weather that everyone has mentioned here is at least like 10C hotter than mine and my engine temp is just rising up to 110C while I'm in C Mode. The temp is at 103C and I just sprinted until the next red light which would be just like two blocks and it gets up to 112. Even though the outside temperature is showing 12C but when there's a fair amount of rain pouring. The outside temp should be around 8C and it would be freezing if you open the windows yet the temp just comes up.

I followed up the thread and I just wanted to know if the fan, oil temp sensor and some others would be just the case or is there anything that I could add up to the list to check?

Mazspeed

Absolutely one of the most absurd advices I have seen in some time other than the guy trying to sell cans of horse power with $30 dollar bottles of octane booster.
Nobody in the racing world believes this for one second.


While Royal Purple is a very good oil and I use it in some of my cars, it by no means is going to change the oil temperature of the car to any degree where a secondary problem exists.


If you change your oil to ANY synthetic, and then go to Royal Purple, you will find no improvement in any way shape or form as far as temperature drop.


It's crap like this that I see where real experts laugh at stupid advice gained from the internet.