I've have a bit of an oil/grease problem with my shutter too. It means I usually do a wet cleaning after I use it...it's not too bad, but even a small speck of dirt annoys me.
Someone I work with has a Nikon D3...he took it to the local Nikon service centre (wish there was a local Canon service centre near here!) for a service, and mentioned to them that he was getting a bit of splatter from the shutter. They took the camera and replaced the shutter and sensor!! (no charge - it was under waranty)...almost made me want to switch to Nikon 
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