Which model of relay and for which system? Good tip about the oil filter.I hear a lot of concern on here about the oil-filter bung backing out. I've started to paint a dot on my oil filters as an easy way to glance down to see if the oil filter has moved at all. (I might have learned this trick here)
That, and as already stated - definitely carry a spare relay. I've been through two in 4 years and 6-7k miles of ownership.