I refuse to pay "The Man" so I have done my 2nd oil change on my 2008 1200L, the first one went great I used the conventional HD oil and Filter no mess not much to clean up. This last one 2 weeks ago I decided to use Mobil 1 synthetic v-twin oil and an HD Filter and not much went right, I started off by making a mess on the floor both from the drain plug and the filter. Cleaned that up and rode off, then I started to notice a lot of oil on the battery and oil tank covers and even more on the engine and tranny. I'll let the picture speak for itself.
Question #1
What could I have done wrong to cause this?
Question #2
could the different oil be the cause of the leak?
Question #3
What could I do to fix this?

I'm thinking of changing the oil again this time using the HD brand oil or should I not even bother.

 

Looking at the pics it could possibly be the rocker cover gaskets failing. they have been known for leaking. Mine started leaking at 2,000 miles, went to the dealer and got them replaced under warranty. But being an '08 you might be out of your warranty though.

 

might have over filled the oil. have you checked the oil level?

 

Rocker Gasket,,, my 08' Nightster did the same,,,, dealer fixed under warranty. Mine started leaking after switch to synthetic,,,,,, coincidence?

 

My '08 leaked too, Dealer fix. next time I'll be doing it. seems to be common.You may get away with Re-torquing the bolts. Do all the head bolts too.

 

I thought about this too, its towards the top of the dip stick, maybe I'll drain some and see how that goes before doing anything else.

 

The oil on the battery is probably from your leaking rocker box, and the oil on your oil tank cover is probably coming from your air filter because you over filled the oil tank giving you the notorious Sporty oil blow-by/puking.
The picture clearly shows a leaking rocker box. Switching from HD to the Mobil synthetic has nothing to do with it......Throwing syn oil in a motor that previously ran dino oil is based on older high milage engines where the engines would get completely gunked up inside and basically cake over the gaskets preventing the engine from leaking........These people then switched over to syn oils that had cleaners which removed the gunk covering the old gaskets and the engines may/would begin to leak. Answer to 1) A couple of issues could have lead to the rocker leaking: getting on the throttle too much too many times before the engine was actually up to sufficient temp to handle it, or just bad gaskets/install of gaskets, or the bolts just worked loose.
Answer to question 2) NO!!!
Answer to question 3) Take it to the dealer and get it fixed under the warranty, or buy the manual & gaskets to fix it yourself.....I'd say warranty it. No sense spending your time/money if it's still covered.

 

I wish the warranty hadn't ran out 2 months ago. Guess I have home work for this weekend. Thanks for the info!!

 

Looks like the same rocker-cover gasket problem I repaired two weeks ago; cheap and easy!

 

Rocker box.