Bash Hat

I'm used to my cars temp gauges being pretty much static but the 996 moves around quite a bit. Freeway cruising it stays pretty constant around 180 but during "spirited" canyon runs or stop and go traffic it gets as high as the "0" in the 180, pretty close to the 3rd line on the gauge. Is that normal? My Aprilia bike temp gets the pretty hot when not moving (as high as 225, when normal temp at speed is around 175) with no detrimental effects but how much fluctuation do you guys see? Currently have Joe Gibbs 0W-40 in the motor. Thinking that's too thin for Socal and will switch to 5W-40 next change. Will that help at all?

Ahsai

JG offers 0w40? Or you meant DT40? What year is your 996?

Schnell Gelb

If you read some other threads on this issue the first problem is that the coolant sensor is not at the hottest part of the coolant circulation system. Then there is the accuracy of the gauge. If you can resolve those 2 deficiencies we can discuss specific numbers with some confidence we are all talking about the same thing. Otherwise it becomes difficult to progress beyond anecdotes. The Track guys have this all resolved because a mistake could mean an engine rebuild. They may be a better source of accurate info because they may have calibrated the stock gauge against more accurate instruments with better sensor locations?

Bash Hat

Yep DT40. Car is a 99.

Ahsai

DT40 is already 5w 40. I don't think that will change your engine temp though. Have you checked if the radiator fans are working on both the low and high settings?

Bash Hat

How do I check they are coming on in both high and low settings? Is getting up to the "0" on the gauge cause for concern, keeping in mind it's in stop and go traffic in 80 degree plus Socal temps. Once I get moving the temp drops back down to the 180 range.

Ahsai

That's exactly why I asked. The fans are supposed to turn on when you are in traffic and the engine temp is too high. I'm not saying your temp is too high though. If you have Durametric, you can activate the fans with low and high settings.

Cuda911

No, getting up to the "0" is not cause for concern. If it goes beyond that, still not really a concern, but I'd start looking for why.

Here's after an hour through the desert at 90 to 100 mph:

Bash Hat

Thanks Cuda. My gauge is right around where yours is when I'm moving at speed. Just gets up to the 0 when stuck in stop and go typical Socal traffic or getting on it going uphill in the canyons for a prolonged period of time.

johnireland

The 0 on 180 is fine in summer stop and go traffic or hard driving. Mine goes to the far right side of the 0 when it is really hot and this is all fine and normal on my 2000 996. On my 2013 GTI the needle never moves, just sits at 180 or whatever it is and that is it.

Bash Hat

👍 Thanks. That puts my mind at ease.

JTT

Also check that your rads are clean and free of debris that gets picked up off the road.

Quadcammer

Sounds fine but if youre interested, you can remove the position 19 and 21 relays and jumper them to see if you low speed fans come on. if not you may have a dead resistor.

And definitely clean out your rads (bumper off)

dan_189

When was your coolant changed last?

Porsche says it's lifetime coolant but that's probably not a great idea.

ejdoherty911

How many miles does your car have? Have you changed the coolant? It's not lifetime. By lifetime porsche means until something else breaks that will force you to change the coolant anyway.