Rallyeporsche

Does anyone know what the "normal" spread is between the water temp. and the oil temp.? Today at freeway speed and an outside air temp of 70, the water temp was 194 and the oil temp was 225.

pfan

You'll become very familiar with those exact two numbers (unless you have Sport or Sport Plus selected, where you'll see ~200 on the oil temp). For some unknown reason, Porsche has decided that the water temp. will never indicate any higher than 194. I guess they figure we can't handle the truth.

trysixty

194 is a fixed water temp number, used to be 200 before porsche changed it with an software update. might as well remove it off your MFD vehicle setting. Oil temperature without Sport on I've seen from 225-232F, with Sport or Sport+ 205-207.

LexVan

I'd also note the lag time for the oil to come up to proper operating temp is pretty significant.

Water temp fast.

Oil temp foreverrrrrrrr.

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NoGaBiker

I don't know about this delta between oil temps in normal or Sport. What's that about? I guess I'm wondering why they let it run at 225 in Normal if they have the ability to keep it at 200-205?

LexVan

Fuel economy. At 225 ya get more mpgs.

In sport modes, they know you're getting on it. And can run a cooler loop to keep the motor happy and the hps up.

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trysixty

I never drive in non sport (normal) mode now, but I seem to remember sport mode coming up to oil temperature faster than in non sport mode. I try to keep the rpm below 3500 until oil temp reaches over 150F.

oldman40

i can tell you that when your water temp does get way above 194, the gauge will show it... ask me how I know!

romansroad

Glad to see its not just me. At ambient of say 50 f, I have seen it take 10-15 to get water temp up, and much much longer for oil. Was wondering if I had a thermostat issue....or , for that matter even wondering IF the 991 has a thermostat. Ugh. As a guy with some serious wrench desires, I miss not knowing or even being able to get to basic parts of the engine.

LexVan

Engine? What engine? I've never seen my engine.

romansroad

you are too funny!

scatkins

Yep Agree.. I don't know where this perception came from that 194 is just an automatic display value. I can only assume that perception exists because the 991 is fairly good at maintaining that temperature.

I've hit greater than 194 that under heavy loads when going through mountain passes.

That said (and this has been discussed in multiple forums and threads) I'm much more concerned with oil temp from a warm up perspective. We had a fairly good thread on this subject, although it may have been a different forum (can't remember).

But if you evaluate the Mobile One viscosity curves, what you find is that there is something of an elbow right around 90F.. And above that temp the change in viscosity between that and 180deg flattens out and there isn't a huge change in viscosity. So from a "wear" perspective if as a rule of thumb you wait until your oil temp is about 100F, before inducing high RPMs you should be in good shape. That doesn't mean don't drive your car below that, it just means take it easy until you achieve at least that that temp.

At the high end on a water cooled engine I switch to water temp as an important factor. And usually you know when you need to be looking at it (i.e. mountain passes etc).

it isn't that Oil temp at the high end isn't important, it is just that usually if your water temp is Ok, so will be your oil. (at least on a water cooled engine, on a air cooled engine it is quite a different situation and as most pilots of aircooled piston aircraft know as well, we live and die by oil temp. ).


As far as the rather slow time in a rise in oil temp in the 991.. It is a very large sump. So it takes a while for the temp to come up as a whole, that said I'm guessing the oil temp is measured in a sump somewhere and not necessarily at the cylinders (I'm only guessing) so that even when you are reading 70F, I would bet the actual oil temp on the cylinder walls and bearings is higher than that.

rnl

It depends. The water temp will reach the 194 fake operating temp in a few miles regardless of how cold it gets. Oil temp is another story

It's 0w-40 oil and will flow at low amd high ambient temps.

The 194 normal reading was fixed was a result of a software patch on my car back in 2012. The Porsche service supplement manual states it represents a range of operating temperatures.

When the car is cold just don't nail it. Warm it up by driving

pfan

The 194 number is straight from the 991 SIT:

It would appear that the normal operating temperature is actually 221 f.

Psup4s

Took my .1 in for service for possible thermostat issue due to slight over heating. while at the dealer, I saw a .2 GT3 being serviced for over heating and coolant line problems. Any one else having this problems?