30hp 4 stroke oil

belairbrian

Petty Officer 1st Class
Joined
Aug 21, 2009
Messages
360
So I just bought this boat with a 30hp 4 stroke. seller says he just changed the engine and gear oil. Said he used Sierra synthetic engine oil. Even gave me an extra bottle. Said it was $12 a quart.

So tonite I read the owners manual and find this:

IMPORTANT: The use of detergent oils, multi‑viscosity oils (other than Mercury or Quicksilver NMMA FC‑W
certified oil or a major brand NMMA FC‑W certified oil), synthetic oils, low quality or oils that contain solid additives are not recommended. (emphasis added)

So should I drain and refill, or is this oil fine? The Sierra Full Synthetic has a NMMA FC-W certification.
 

wired247

Lieutenant Commander
Joined
Oct 8, 2011
Messages
1,557
Re: 30hp 4 stroke oil

I'd probably drain it and refill in the next time you are due for an oil change. If it holds the cert its good to go.
 
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