Not only is 8.0 not supported, but it will not update the virus definitions either. The current DAT files removed support for 8.0 quite awhile ago. 8.5 is the oldest McAfee that still works with the current DAT's.
Though you think they have been updating, my guess is that they have not and you have been unprotected in the interim.
Think of the biological analogy:
Go in to your doctor for your yearly physical. He/She asks you if you want a Flu vaccination. You say yes, so s/he goes and retrieves the shot, which is dated 3 years old. S/He states this to you. Would you take it? Would you expect this shot to protect you from this years flu virus? Would you ask for a more recent vaccine? Or, would you take the shot and leave, thinking that you are protected? Hopefully the shot won't make you sick.
In the virtual world, 3 years of bad or no updates, is an eternity. Only great luck has protected you.