Feeling neighbourly I offered to do some work on the local farmer's sadly neglected 1987 Honda XL600. (There's no stickers on the bike so I'm not sure of it's exact model designation; I suspect a XL600L.) I managed to get the buckle out of the front wheel OK and thought I would change the oil for him, as the bike had been sitting for a couple of years. I drained the engine oil from the frame downtube OK, then I noticed a 17mm drain plug in the lower gearcase, just in front of where the engine number is stamped. I removed the plug and about a litre of what I took to be engine oil came out (it was thin and black). He doesn't have a manual or handbook, so I have a couple of questions maybe y'all can help out with. 1. Is the gearbox lubricated with the engine oil or does it run in separate oil? (i.e. what is the oil that I drained through the hole with the 17mm plug?) If the answer is yes, can you advise what grade of oil and where do I fill it and check the level? (I suspect the round slotted plug in the centre of the left hand engine casing, but confirmation would be nice.) The bike looks similar to this.. All (useful) responses greatly appreciated!