decades ago an experienced racer told me that he changed his oil (& filter iirc) after each Saturday night session & at the time I had just accepted it as gospel thinking how toxic that a dirt track environment must be. it certainly does sound excessive & later someone else has said they changed the oil every time but only the filter after several races. I am open to thoughts/suggestions. RR
You said the cam is broken in already and I assume the rest of the motor is too. So you don't need break in oil any more. Now you need racing oil for flat tappet cams. There are many oils that are suitable for this. Take your pick.
As a hobby stock you will probably put more or less 30 laps on the motor in a night including hot laps , heat race and feature race. If everything is working as it should there should be no need to change the oil after one night of racing.
There is a long list of things that could compromise the life of your oil caused by things not working as they should be.
Here are a few things in no particular order. This is not a complete list.
1. Oil contaminated with dirt
2. oil overheated
3. oil contaminated with water/coolant
4. oil contaminated with fuel
5. oil contaminated from parts failing inside the engine.
