I put oil on the race track before the race
Do you think that they will find out what you did?
I don't think they'll ever know who did it
You should never put oil on a race track. People could run into other drivers on the track and it is dangerous.
It's fine I don't think anything bad will happen
You need to try to warn someone before the race gets started. Someone could absolutely get injured or even die because of the oil.