Ok, thinking of buying this rope second hand, but they guy is unsure of the size.
He bought it 4 years ago and it's either a 10.2mm or 10.5mm Edelrid 60m.

Also, is it advisable to buy a rope that's been sitting around that long. Apparantly he's only used it about 4 times or so within that time.
So what is the shelf life for a rope?

It looks like a 10.5 be carefull about buying a rope from strangers or car rides with strangers!Unless they have candy!

A rope can last ten years! providing it is kept correctly like no damp mouldy kitchen cuboards!
I always say if you have not climbed with the guy you wont know what poor tourture that rope endured!Always buy from some you climb with that way you have seen what has been done to the rope.

Perhaps overly cautious......

But I firmly believe in replacing all soft gear every 5 years.
(I have noticed my latest slings even have datestamps by the manufacturer)

By the way, how much are you going to save by buying a 4 year old second hand rope vs. a new one?
Is that the price your/your climbing partners life is worth?

I bought my first rope second-hand. It was two years old, used probably once a month. A Beal (Top Gun?? - can't remember) 10.2mm, 50m. It lasted me three years, until I had the spare cash to treat myself with a new one. It's now probably lying somewhere in my ex's cupboard.
Have a close look at the sheath, to make sure it's not frayed and worn, and scrutinise the core, by feeling and bending the whole length of the rope. If there's no sign of thinner parts in the core, and when you fold the rope onto itself, it shouldn't fold flat at the loop end - ie the rope shouldn't be able to fold 100% onto itself at any point.
A good idea is also to make sure of the length of the rope - you don't want to be caught short.

I'd be careful about who you take advise from. As they say, The road to hell is paved with good intention.
IMO if your asking for advise you have doubts and if you have those don't do it. But Most importantly learn the trust your instinct you will need it on the Rock.

Garvin
PS if this sounds like BS I'd go with what Hann said

If the rope genuinely has only been used 4 times, there will still be those little tags at the end saying how long and what diameter the rope is.