Chain lube

[darrsi]

Old engine oil saved from either a car or bike oil change with an old paint brush for application, after every ride I give it another coat.  Only problem is it's very thin and just falls off the chain if you ride in heavy rain, but for dry weather riding it's perfect, and costs nowt! 

See, i don't get that at all.
Old oil will have fine metal particles in it, and as you say will be thin because it's lost it's properties.
If you're gonna use engine oil, at least use new stuff.