The level of oil when at idle speed has to be below the first baffle plate in the tank,
Even when you have the cap off rev the engine slowly to around 5k and see if the level is below the first baffle,
The baffle is designed to remove the air from the oil before going into the tank and being picked up to the engine feed,
Failing to do this will cause air bubbles in the oil this can be picked up then the oil is fed to the bearings with air in and this can cause one of the big ends to fail,
EG see the top baffle in this tank the oil level should be just under this on idle, only check oil level with engine running
If over filled this will pressure and send the surplus oil to the oil catch tank if one is fitted,