How does one determine if they need one?

Oklahoma gets hot in summer...I've topped 230F pretty easily...

At 230 I wouldn't worry about it. I had to work my car pretty hard to even get to 245...If you consistently see 260-280 due to your driving style or usage I'd go with a cooler..

Rofls. People hear "oil overheating" and they are assuming this will happen in normal driving situations, regardless of temperature?

Before you install an oil cooler you should consider the following:

1. Factory warranty or factory extended warranty ramifications.
2. Consider having your Nissan dealer install the Nissan Motorsports Oil Cooler, part no. 21300-SS370.
3. If you are not one who can wrench it will be much harder to remove the oil cooler should the oil cooler, and its installation, be considered a violation of your factory Nissan warranty. A competent mechanic can discern whether an aftermarket product has been installed or not.

No, in my case, I don't know how hot oil should be "allowed" to get...

What's the "smoke point" of engine oil...?

You'd be surprised how many people really do need an oil cooler. Hard canyon driving in hot weather puts the oil temps into the danger zone.

Track days?? Forget about it. Good drivers will have the 370Z into limp mode in a just 3-4 laps at some tighter tracks.

If you daily drive your car, and with no tracking or aggressive driving, then an oil cooler would be unnecssary.

I am really surprised Nissan missed the boat on this. THe 350Z has better oil temp behavior than the 370Z, surprisingly.

Most shops should charge about 3-4 hours.

Nissan says 280. I will assume their engineers determined this temperature because of the advances in todays materials technology, oil lubricity properties and the gazzillion dollars Nissan has invested in their testing facilities to develop a state-of-the-art high performance engine for street use or they asked the receptionist at Nissan headquarters to pick a number between 250 and 300.

I've seen musings of what the average oil temp on the 350Z would be - do we have an actual number?

The smoke point of synthetic oil is well over 400F when new, however this temperature lowers as the oil becomes contaminated with age, at end of life it could be just above 300F. So it's really not a problem for most people, just stick to quality synthetic oil.

If you're into HPDE track days, a cooler is mandatory to keep to car out of limp mode.

I drove my Z fairly hard on the street tonight in over 80 degree weather and barely made it to 220. You really do have to be canyon carving or on the track to be worried about this.

Just for reference, my Mobil 1 in my truck had about 6000 miles on it, and its flashpoint was still around 400 according to Blackstone labs.

It's all in how it is driven. 6000 easy highway miles with synthetic and it will come out in good shape, probably could even stretch to 10000 if it is almost all highway. But do 3000 hard miles with a track day or 2 and it will beat the hell out of your oil. It is a good idea to get your oil analyzed once or twice to see what your driving style is doing to the oil.

Oh I know, I was just pointing out that its worthy to note and some slight proof that normal driving wont do much at all to your oil. I also found it funny that Blackstone said my motor is still breaking in at 13000 miles - how's THAT for blowing your mind? :) haha