It seems that my engine is getting damaged all the time - and I don't know why. I couldn't see any smoke so it's for no apparent reason like shifting too quickly. Mostly running normal mix and having used a wet setup (first 40 laps were dry) I can't imagine overreving too much. Granted, this was the third race for this particular engine (was at 94% in practice, didn't check in qualifying / before the race) but I didn't notice a decrease in performance at any point during the race. The color changed from light brown to this to this over the course of the race.