a 5 ounce egg but how can i help my chook next time?

[chicknrt]

i have 4 lohmann chooks, nearly a year old, they are fantastic egglayers, i have got 4 a day every day, usually the eggs are just under 4 ounces but one of the chooks occasionally lays bigger, the one she laid today is just over 5 ounces and i saw that she struggled a bit (came out of the nestbox and laid it in the cool long grass, imagine that was bliss for her!). i have read that if she needs help to drop some veg oil onto her vent, or even give her a bath? is this right please. if she does get into trouble i want to be able to help her. she looked fine as soon as she laid it. how big is big?? this looks like a whopper to me!