서킷을 다녀오면 꼭 오일교체가 필요할까?/현실고민 설명창에 요약있음

First off, please understand that I am a complete beginner, and this is based on my experience driving on the track. I want to make it clear that I am not writing this after driving like crazy. First off, I spent 300,000 won on gas for the round trip from Daegu to Inje, Gangwon. I used 60% of the fuel for two sessions on the circuit. Total, I spent roughly 400,000 to 500,000 won just on gas. I haven't had the engine oil checked, but it needs replacing considering the mileage. I didn't change the differential oil before going, so if I had, maybe I should have done it one more time? The brake pads and things like that were practically brand new when I went, and they are still the same. As for the tires, the sidewalls are quite worn out. Since I have separate wheels and tires for the track anyway, I think I'll be able to drive for two more sessions. In conclusion, at first I was nervous thinking I'd have to replace this and that after a trip to the circuit, but once I actually went, it was just okay. (Of course, beginners and advanced drivers are different.)