Mercury DFI Oil and Fuel Question Optimax

[JeffM]

I have a Mercury 150 Optimax that is about 3 yrs old.  I generally fill the oil reservoir with 1 gallon of Quicksilver DFI oil and use about 1/8 of it by the end of the season.  Is it ok to be using the same oil the next season?  The last two years I have replaced it but I feel like I am wasting so much and its pricey.  I am also considering using ethenol free high octane fuel.   I am currently using regular 87 with 10% ethenol and treating it every time with StaBil marine.  What option do you feel is best?  I am concerned I could also be introducing issues with high octane fuel and the motor has been running great but to be fair its pretty new.  Any input would be appreciated.

 

Thanks

[BAZOOKAJOE]

Just top off your oil. No need to change it. And you definitely want to run the non-ethanol gas.