I was using a 16Mhz crstal for my project,when I switch the crstal to a 4Mhz crystal,everything fine,I wonder why?i found on the internet for calculating the capacitance,it give this fomular

C = 2 x ( CL - C s)
Where C is the capacitor to be connect to the crystal
CL is the crystal load capacitance
Cs is the capacitance of the crystal casing plus the circuitry capacitance
My 16Mhz crystal have a load capacitance of 30pF,the Cs is assume to be 5pF,then my capacitor will be 2x(30-5) = 50pF,but the MCU Datasheet specify that for a 16Mhz crystal,the capacitor should between 10-22pF,so which one is correct?