Everyone with oil temp issues

wstar · 06-25-2009, 03:36 PM

Quote:

Originally Posted by kannibul

OK, has your oil temp gone over 230F by going 75 in a 65?

I'm saying that someone who is going over that has to be doing something illegal - more illegal than those who typically drive the same stretch of road(s)...

And, how exactly does one "push" the car to the point of overheating the oil and going into limp mode?

I don't drive mine like a saint (at all), and I've yet to...

Oil temperature has nothing to do with vehicle speed, it has everything to do with ambient temperature, engine revs, engine load, and airflow to the radiator/engine. To give a silly example, if you were to drive down the road in first gear at 6,500 rpm for several minutes straight (which is way under most street speed limits, much less highway), the oil would overheat in most ambient conditions. At that low vehicle speed you're not getting much cooling to the engine, and the high revs are going to cook the oil, and no laws have been violated.

Following the same logic it *is* possible, on a hot day driving around on smaller streets with lots of uphill, to keep the revs high while nailing it around a twisty set of corners and streets without exceeding the speed limit, and overheat the oil. If you're a particularly smooth driver you could even do it without attracting much attention or appearing to be doing anything reckless. Most people won't, but it can be done.

"It's illegal to overheat your car" is nonsensical, don't give Nissan ammo to avoid the issue with.

ChrisSlicks · 06-25-2009, 04:59 PM

I'll take auto-cross as an extreme example of low speed driving. Our auto-cross site has a speed limit of 70 mph, we basically drive the whole course in second gear. There is lots of hard acceleration and hard braking with the rpm consistently in the mid to high range. At the last event I was hitting 260 degrees in 100 seconds. If I were to keep driving like that the temperature would keep rising and eventually hit limp mode, but fortunately auto-cross has a long cool down period between runs.

I could drive half as hard on the street and still get there, but it would likely take 3 times as long. Acceleration is what generates the most heat as that is when there will be the biggest bang (fuel combustion) and when the VVEL is the busiest. So on the street, switching between full throttle acceleration and braking you can still hit limp mode in no time, speed is irrelevant.

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06-25-2009, 04:59 PM	#2 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 654	I'll take auto-cross as an extreme example of low speed driving. Our auto-cross site has a speed limit of 70 mph, we basically drive the whole course in second gear. There is lots of hard acceleration and hard braking with the rpm consistently in the mid to high range. At the last event I was hitting 260 degrees in 100 seconds. If I were to keep driving like that the temperature would keep rising and eventually hit limp mode, but fortunately auto-cross has a long cool down period between runs. I could drive half as hard on the street and still get there, but it would likely take 3 times as long. Acceleration is what generates the most heat as that is when there will be the biggest bang (fuel combustion) and when the VVEL is the busiest. So on the street, switching between full throttle acceleration and braking you can still hit limp mode in no time, speed is irrelevant.