OK, so I did my first oil change on my 2007 s40 tonight.  When I went to drain the oil I unscrewed what I thought was the oil drain plug.  Only about a half cup of oil came out which struck me as odd!  I put the plug back in and found the correct drain plug way on the bottom of the crankcase.  (Who'da thought it'd be there!)  I finished the oil change, including filter, buttoned everything up and ran the engine.  No leaks, oil level is good.  The issue is that now when I put it into gear there is a loud clunk as the tranny engages.  I have looked in the Clymer's and it mentions nothing about any kind of fluid other than oil.  The stuff I drained out first looked just like engine oil (dirty!).  Any ideas if one has anything to do with the other?  

I have attached a picture of the plug I pulled out first.


Thanks in advance!

I get the same clunk going from 1st to 2nd.  It seems louder than before...

I'd have to go look to see exactly what oil I used but I know it was specifically for a wet clutch.  Got it from the dealer so I'm assuming it's right!  Drove the bike a few miles and everything seems to have gone back to normal.  

Thanks for all of the advice!

Newbies who don't know shouldn't suggest.

What he undid had nothing to do with anything -- it is a right angle oil passage drillway that they had to tap to plug it when they were done with the drilling.

It is now there to give a spot to return the oil flow from an oil cooler set up.

Funny, I only hear a medium low clunk    

Seriously, in a multi-disk wet clutch system you will always hear a clunk because there is always some friction between the clutch disks and the drive disks due to contact and/or fluid (oil) between them.   Unlike most cars (that use a single dry disk), the wet clutch disks will continue to spin even if you hold the clutch in for an extended time in neutral.   The impact of the clunk when shifting into gear is generally proportional to how much friction exits.   When you change oil, the new oil has more viscosity which may produce a louder or different sounding clunk.