Adding olive oil?
Should you put olive oil in your homebrew?
Why use olive oil in your homebrew?
Your yeast need oxygen for a happy and healthy fermentation. Yeast use oxygen during the lag phase to synthesize sterols and unsaturated fatty acids for its cell walls. If there is not enough oxygen, the yeast can not grow and die off early. Low oxygen leads to stalled fermentations and off-flavors. This is the reason you need to shake the carboy before pitching your yeast.