Knock, Knock....

[dabull]

who's there....ok, couldn't resist...but heres the issue???

I'm getting a knockin that sounds like it is coming from between the heads or towards the back head...turn the volume up and check out these videos and let me know if this sounds like your bike, or whether or not you think I have a problem...

This one from straight at the bike....



This one pointing at then away...



Thoughts???

ok, just went out to take a look at oil level...it is a little low...level is right at the "L" level (which brings up another question till i change oil...can i mix oils as i don't have a clue as to what grade the dealer put in but i have 10w 30 penzoil in car from last oil change)..

so...
1. knocking
2. oil mix

Thanks in advance...

Derry