Honda marine.com most common questions:
What type of engine oil should I use in my Honda marine outboard?
Honda engines are developed, tested, and certified with petroleum based motor oils as a lubricant. We recommend Honda Marine 10W-30 FC-W engine oil or 5W-30M engine oil (see your owner’s manual for recommended oil) available through your local Honda Marine dealer. Honda FC-W Marine engine oil is specially formulated for use in marine engines and has several advantages over automotive oil. See your owner’s manual for oil change intervals.
Honda states to use 10W-30 FC-W engine oil. i did a quick search on the web and found the Honda Marine 10W-30 FC-W engine oil for $5.75 per quart with free shipping, cost less than most synthetics oils and engineered for marine use.
I've spoken with two seperate Honda Mechanics regarding my 225 and my 8hp and they've both told me not to use synthetic - just to use 10/30.....
A mechanic at Clemens marina told me wait tell the engine is broken before you start using the 10w-30 synthetic oils, didn't ask why.Was thinking about this the other day. Most outboards spend their running time at half to full throttle. I would think that a synthetic would be beneficial. Anyone running sythetic in their 4 stroke? My Suzuki spec's 10w-40.
Most oils today are "paraffin" based. Paraffin oils make excellent lubricants, they don't have chunks of wax floating around in them like the folklore would lead one to believe, paraffin oil and paraffin wax are not one in the same. Modern refining processes pretty much level the playing field with base stocks anyway. Besides, Pennzoil and QS haven't used Pennsylvania oil for decades.MP: I would not use any Paraffin based motor oils in anything. Check crude source on Pennz and QS.