My 850's blowing oil all over the tire

Hey guys I'm new and have been reading alot of post about oil blowing out of my oil tank down to the air filter and then all over the bike. Its a major issue.
So what I'm to believe i should use 50 weight oil and only fill it 1/2 way between the add and full mark? Anything else? i mean anything else that I might be missing? Any advice newor old would be wonderful and much appreciated.

Thanks everyone - i really want to get this beautiful bike running like a sewing machine...

And do that filling to the midway mark AFTER the bike has run for a while, to return the oil in the sump to the oiltank. Incredibly common for someone unfamiliar with the wet-sumping issue to look in the oil tank, see it's low, and fill it. Then he starts the bike, the oil in the sump gets pumped back to the oil tank, overfilling it, and yes, it's gonna spew....

Might also check to see that your chain oiler isn't the problem, or part of it. Most people, I think, block off the tube with a bolt and a hose clamp. I did, anyway. I can lube my own chain, thanks!

Good luck - and welcome to the forum. - BrianK

When you've got it running like a sewing machine, can you run up some curtains for me?

Full Auto - The curtains are on the way....This bike is awesome. It was built from a heap of parts ofver a few years. 8)