Engine Rocker Gasket Replacement

pejo 206 my engine The engine top cap is missing from the rocker gasket engine oil I changed it about 2 months ago there was no leakage 2 -3 days has been missing from the rocker gasket The oil level of the dipstick is about 2 fingers over 2 fingers because the oil has lost too much or the gasket has lost its feature. Does engine oil drain while changing, thanks.

NO OIL LEVEL REQUIRED TO REMOVE OIL, DECREASE, DON'T IMPORTANT IMPORTANT BECOME A FAULT BUT NOT CHANGE ASAP.

THE GASKET LOSSED ITS FEATURE I FORGOT TO WRITE THIS PARDON OIL THAT HAS BEEN VERY PASTE, NOT FROM THE CONTACT