OptiMax Enginer Oil - What to use?

Spoke w/ Mercury reps today. They said the Optimax motor could use the DFI or the Quicksilver Premium Plus. They said using the Quicksilver Premium Plus would not void the warranty. However, they did say that if you use the Premium Plus you should run 89 octane gas. If you run the higher end DFI oil you can run 87 octane. I asked if I could switch back and forth and they said that wouldn't cause any problems.

BPS has Penzoil Synthetic under $10 a gal. (Better Hurry) Been using this for 6 yrs on my 175 Opti.

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