Just bought a new 175 pro XS,the mech. told me to use prem. plus.They gave me 2 gallons and it was very black oil.Was this opti oil? Got my jug filled at another dealer,asked for prem. plus. I was pouring it in and noticed it had a blue tint to it.I stopped,I'm guessing these are 2 different oils. Can these oils be mixed?