927 at 40:1?

[Dirtscooter5]

I have run the stihl silver oil forever and never had a problem with it I just like the smell of 927 plus I think its good oil. I switched from the silver stihl oil to 927 a few weeks ago at 40:1 I have already noticed after several tanks thru my 362 it is developing a wet oily look around the muffler port. I don't want to gum up my saw should I switch back to the stihl oil or try 927 at 50:1, or just not worry about the oil residue and keep the 927 at 40:1. BTW all my saws are stock. 241, 362 and 660.
thanks