I have some 6 or 7 year old Reverware pans that are teflon coated that have been in the box till I opened them the other day and was wanting to know how much oil should be used in them?Do you need to coat the entire bottom of the pan in oil or or can some of it be dry?They are nice pans and I don't want to ruin them and I have heard not to use the spray like pam on them.Also I only cook with them on medium to low heat.