Once I warm up my GS500 up and during idle it knocks for a sec and the engine idle  drops and stalls sometimes. I have read this is due to cam play, can anyone tell me a cure or is this something I should live with? Maybe a Carb adjustment or oil change with different oil type?

Knocks only when hot, only at idle, and stops knocking when engine is speeded up to a fast idle or faster?  If so it's probably the cam knock if your GSF is older than 05-06.  Suzuki finally fixed it with a camshaft change after that.

I had it on my 97 bought new that I rode from 99-03 when it was totaled and replaced with my current 02 model which also had it at first and it has over 100k miles on it now.  After first hearing and diagnosing it on the 97 it went away around 50k miles after I changed from 15W-50 Mobil synthetic to 15W-40 Rotella T dino juice.  Changed the 02 to the same Rotella T not long after I bought it used with only 4k niles on it and cam knock went away around then I think, it was a long time ago now.  Can't say for sure oil change fixed it but it's long gone and it's harmless anyway if that's what you have.

Yes when it's hot only at idle, goes away when engine is speeded up. I have a 2004. I was reading about the problem online and stated the same thing you did. I'm going to give it an oil change using the oil you recomended and see if that helps. BTW where is the oil filter located?

Thanks for your advice...I was worried that the motor was toast. 

Oil filter is just below your oil leak at bottom front of engine, cover is held on by 3 small acorn nuts that result in frequent broken studs for new members.  Easy as she goes when tightening those.

Is there a known torque spec for the acorn nuts?

Don't got a book in front of me but i think its 10ft/lbs....with that said 1/4" ratchet and just snug them up, take it around the block a few time and check for a drip. I don't go by spec on these things because all you are doing is seating a rubber gasket. Little to no pressure is in this area.