I was told to only use Yama lube or Mecury in the newer Yamaha motors - roughly 2004 and newer.
It has to do with the metering system - it needs the right viscosity oil to function correctly.
At 5,000 RPM - bad things can happen quick. That bargain oil might not be a good deal.
It sucks spending $20.00 - $25.00 a gallon but better then $12,000 for a motor
The new motors really do not use that much oil. Keeping the RPM around 4,000 helps. Running WOT or close is where oil comsuption is the most.
FWIW: Cedar Creek in Delaware used to sell Yama lube by the galllon - in your jugs. Not sure if they do anymore or not. With diesel at $3.00 a gallon - not worth the long drive to try and save a few dollars on lube.