The car ran beautifully. I was out on the track passing people left & right, and lost the back end coming through the left bend which follows Riverside curve. I probably backed off the gas fractionally to tighten up my line, and the car (as it turns out) was set up rather loose. The back end came around, I wasn't able to catch it, so I went two feet in (i.e., clutch & brakes) and we spun off the track at ~80 mph, through the dirt, and into
the only mud patch in the entire Bakersfield area. I have no idea why there's mud there, in the middle of August in 100+ heat, but there was and it sprayed through the open windows as we described a 180-degree spin in the mud patch. We ended up needing a tow from the local tractor, as the rescue vehicle almost got stuck trying to get to us.
Anyway, I cleaned everything up (including dismounting all four wheels and cleaning mud off the inside of the rims and the brake/suspension) and got back on the track later that day, but the slide through the mud had loosened up the oil return line from the crankcase breather, and I started losing oil pressure (i.e., below 30 psi but above red) after 4 laps and decided to call it a day rather than risk my motor.
Hopefully there's nothing more serious wrong than a clogged oil filter screen. OTOH, if I've damaged something, it's the opportunity to replace it with something better
Lessons:
1) tire pressure is critical. After my spin, I played a bit on the skidpad, and with only 1 PSI difference between front and rear tires I couldn't catch the back end when it came around. With 3 PSI difference it was child's play to catch the slides.
2) slides are harder to catch on slicks than on street tires. I've driven on slicks before (Russell Racing) but clearly need more practice before being entirely comfortable pushing their limits on a roadcourse.
3) 600 HP + 14" slicks + good brakes + good suspension = one hell of a roadcourse car. As an exercise in one of the sessions, I drove around in 4th gear (including the 40 mph corners) just to practice my lines. Even in that mode, I still ended up stuck behind M3s & Porsches, and had to pass them to avoid frustration. It's not that I'm such a terrific driver; the car is just a monster.