- A couple quarts of oil
Distilled water - antifreeze not needed and typically not allowed on track.
Unique parts, such as fuel pump or fuel filters - anything that's not readily available that can screw you out of a fun weekend.
Floor jack
Jack stands
Complete set of tools (though you don't need a complete set of wrenches or sockets if you only use certain sizes).
Torque wrench
Lug nut adaptor for torque wrench
Air pressure gauge
Tire temperature gauge
Compressed air tank or small compressor
Various sized zip ties
Paper towels
Glass cleaner
Liquid detailer
Soft scratch-free cloth
Car numbers - static, magnetic, or paint-on ("Glass Chalk" or "Window Chalk")
Safety wire
Duct tape