That's interesting, I'm treating all my fence boards and posts in used engine oil in wheely bins. I thought about using it as creosote to apply with a brush. Does it work ok like that, you seem to be quite knowledgeable in old oil uses!
I was going to get some of that tarmac reviver stuff that you put on with a roller. It basically just colours it and improves the appearance, but someone said I can use old oil instead. Not sure about this though, I think it won't dry aswell and still be a bit slippy.
I've heard of people filtering it and using it as 'black' diesel.
It works quite well brushed on Geoff, although it does take longer to dry. I did a couple of back gates recently that hadn't been treated for ages and had bleached to a light grey colour. They probable took 3 or 4 days to dry, but dried to a nice chestnut colour!! 
Ok thanks, I've got plenty oil so that's great! I'm looking forward to it now. I love the smell of it!