Not that extreme. Nobody runs a oil temp gauge so you don't realize how very hot the oil gets. Ever get over to Germany to run on the autobahn? That'll heat up your oil.

 

I race cars with oil temp gauges, if the oil temp goes above 125 degrees C I consider it scrap and change it.

If you're running 150 degrees I'm surprised you haven't cooked a bearing yet, assuming your gauge is accurate.

 

Adding to the oil temp discussion based on my C5 Z06 experience, which may or may not be applicable. The C5 Z06 did not come with an oil cooler stock, but does have the ability to monitor oil temp on the DIC. As it was essentially a track day car out of the box, many used it for exactly that purpose (as I did). Almost all found that the oil temp would scream upwards of 300F (150C) in a 20-30 minute track session. Maybe not directly applicable to most C3s, but I bet there are those that really do use their cars that hard. Doesn't take long to get oil temp up well above a nominal 212F or so and as it does the viscosity drops rapidly - to me, that's when I really want a high ZDDP oil in my back pocket. And my engine obviously has rollers not flat tappet.

 

Why would you run an engine that hot, it hurts the engine and hurts performance

 

Oil temperature not engine temperature.

 

Surely one reflects the other?

 

I didn't. At my first two HPDEs I would back off or come in as the oil temp went over 270F or so (this was back in 01/02) - but many don't - they stay out.

I put an oil cooler on mine before my 3rd HPDE. I went racing in 03 and so now I can't really just back off, but the cooler is pretty effective and at my last two races my oil temp was around 240-255F throughout the race.