Hello- I have a Merc 115hp outboard. I noticed that an oily substance is dripping from the prop area. I'm not sure if it is lower unit lube or unburnt fuel. I'm not sure what year the engine is but the shop manual says "for serial numbers 4112635 and up". How can I tell what this substance is? If it is lower unit lube is it difficult to fix and is it safe to use before repaired?<br />thanks<br />chris