It is most likely not the oil, but rather a dirty carb that is the issue. I have been running Blue Marble for almost 32 years plus now and it is awesome!!! The smoke is heavy at first, but get the machines warm and the smoke is gone. I run this is 4 machines, plus my chain saws, weed whackers, etc and I never had 1 problem.
As far as problems with the said machine. All it takes is 1 small particle of dirt to plug or partially plug a carb and create the issues you are claiming.
Signature:
1985 ATC350X
1986 TRX-250R(Soon to be an 87)
2001 Polaris Scrambler 90
2004 Arctic Cat DVX400
2003 Yamaha Blaster
2005 YFZ450
Rip: To many to list........