Question about track oil temperature, pressure, and viscosity
 

So, the Forester oil cooler option plumbed to the heater core lines is not working well for me; still hitting 270F on Laguna Seca, Sonoma Raceway, and Thunderhill Raceway with my almost stock BRZ. Oil results from Blackstone Labs says the Redline 0W-20 is doing just fine, but wear is kinda high. I don't have an oil pressure gauge, so I'm just relying on this video from savagegeese to get an idea: https://youtu.be/cDfFJ5s6IDg

From savagegeese:
0w20 Redline 225F @ 800RPM 7PSI Oil Pressure
0w20 Redline 225F @ 2000RPM 30PSI Oil Pressure
0w20 Redline 225F @ 4000RPM 48PSI Oil Pressure
0w20 Redline 225F @ 7000RPM 43PSI Oil Pressure

And I'm running 50F hotter.

Looking to professionals for how they do it, Toyota Motorsports GmbH with their 2017 86 CS-Cup they are running Ravenol 5W-50 and an oil cooler.
https://www.racingbytmg.com/en/motor...cup-downloads/

Being that I drive less than 5000 miles per year, the car is mainly for trackdays and weekend fun, and I'm prioritizing engine longevity over gas mileage, is there any reason I shouldn't go to thicker oil, a more significant oil cooler, and an oil pressure gauge? Or are there wiser options?

Picture for entertainment:
https://www.racingbytmg.com/wp-conte...p/CS-Cup_1.jpg

High quality 0w-20 is fine. Get a better oil cooler. I like the Jackson Racing oil cooler. The Greddy one is pretty nice as well.

Subaru and Toyota suggest higher viscosity for heavy use while STI sells 5W40 as an upgrade oil, they know more than what we know about our engines!
I use Redline 5W30 for spirited driving and is the thickest oil in this viscosity with very high HTHS.

Question about track oil temperature, pressure, and viscosity
 

If Toyota is using 40 or 50 weight oil WITH an oil cooler, then that should be a pretty good indication of what is required for a track car. If it was a daily driver I'd say 0W-20 is perfectly acceptable. However, since your car is primarily used for "track days and weekend fun," I'd say do what the pros do and invest in a track oriented oil cooler like the Jackson Racing kit, and use thicker oil. Repeated and sustained oil temps at 270 is really pushing your luck, and since Blackstone is already telling you that engine wear is higher than normal...yeah, I'd bump it up a grade or two. You're in California, so cold weather won't be a huge issue for the thinker oil.

You need a better oil cooler.
Jackson Racing and Greddy are popular for 86Cup participants whether Stock, NA or Boosted

See data below

All OE Engine
Jackson Racing Oil Cooler
Motul 300v 0w-20

Streets CCW
Avg Ambient: 90f
Max Coolant: 203f
Max Oil: 221f

Laguna Seca
Avg Ambient: 80f
Max Coolant: 199f
Max Oil: 226f

Buttonwillow
Avg Ambient: 110f
Max Coolant: 212f
Max Oil: 232f

https://i.imgur.com/U5jlXLT.png

You need a proper oil cooler.

PM me. We can discuss your needs more.