Proper Oil

I've got a pair of 2012 BF115's. The manual of course, recommends "Honda" oil, 10W-30 SG, SH, or SJ grade. Two of those (SG, & SH) are obsolete specs, and the third is less than or equivalent to what is currently on the shelves at auto parts stores. Current oil is SN grade.
My question is, is there an oil that is 'better' than others on the shelf, or should any of them be ok? What about synthetic?
Thanks,
Jim

Any 10w-30 will be fine. How long it provides proper lubrication will depend on the quality of the oil. Synthetics will last longer between changes. I use low to middle of the road stuff and check (every use) and change often (when necessary).

I have somewhat of a different perspective on marine outboard engine oil, which I've discussed several times previously on this forum.

Yes, most any 10W-30 motor oil will work, and the current API "SN" specification is certainly fine. Honda specifies API "SG" or higher. However, I'm not a fan of the synthetics for marine use. The key is to change the oil AND FILTER every 100 hours or every season, whichever comes first. If you follow that schedule, then the synthetics are a waste of money. If you use a synthetic to lengthen the time between oil changes, then you will also likely lengthen the time between other critical maintenance checks and requirements. In the long run, that will degrade your engine. If you think about it, if you average 20 MPH on your engine, then 100 hours is equivalent to 2000 miles. BUT that 2000 miles is under extreme conditions. It is somewhat equivalent to driving your car or truck, loaded down, up hill, in second gear for 2000 miles.

There has been an argument made that synthetic oil may actually be worse for a marine engine, especially if it is used for low rpm trolling or cruising. The argument goes like this: The synthetic oil will make your raw water-cooled engine run cooler at low rpms. That cooler engine will tend to allow moisture to get in your oil through condensation and thru looser rings. The water in the oil will dilute it and cause additional wear on the bearings and rings. I'm not sure I buy into all of that, but why take the chance? The engine was designed to give many years of service on standard petroleum-based 10W-30 with oil changes at every 100 hours or every season, whichever comes first.

Your outboard is still under the Honda 5 year warranty. While using synthetics is probably fine, it may "muddy the waters" in the event of a warranty claim.

I do not believe that synthetic oil should be used as a maintenance interval "extender". Oils break down due to contaminants getting in them and TBN additives being depleted as they are stressed and thermo-cycled. This is, IN MY OPINION, why Honda does not come out and recommend synthetics in their outboards. They would then have to justify the added expense and come up with an oil change schedule to suit the public's conception of what is correct. As chawk_man points out, an outboard experiences a different set of "stress factors" than automotive engines including the constant exposure to high moisture levels entering the intake. While there ARE a couple out there that claim "1 YEAR OIL CHANGE" and such...most DON'T. Most synthetic oil manufacturers recommend sticking with the manufacturer specified intervals for maintenance.

Don't get me wrong, I believe in synthetic oil and use it in my late model car. I would NOT buck Honda's recommendations on my outboard though.

I suggest using a name brand, API SN, petroleum based oil until AT LEAST your 5 year warranty expires. Then, if you have weighed all the factors and still would like to "experiment" with synthetics, go ahead. By then, the price of Petro oil may exceed the synth if recent trends I've seen continue.

Good luck.

I personally don't use synthetic oil, just whatever is on special at the time and is a recognised brand. I do change oil more frequently than oil filters (if I don't like the colour or smell) but still stick to the maintenance schedule for filters and other service parts. I haven't heard about synthetic oil for marine use being an issue as chawk mentioned. What I said about it lasting longer is generally true (synth Vs mineral oil) but is certainly not an alternative to following the manufacturers service schedule. At the end of the day I totally agree with chawk in practice with the addition that I like to put my eye and nose on the oil every trip and possibly replace it more frequently (I also check leg oil).

I re read my first post and realised it sounds a bit misleading. Sorry. When I said "lasts longer between changes" I did not want to infer that you should extend the time between changes beyond the Honda service schedule. Perhaps I should have said "performs better over its whole service life" or something like that. "Change when necessary" should have said "change if it's not looking or smelling great or at 100 hours/1 year, whatever comes first". I was trying to encourage a MORE frequent oil change interval and oil checks but it was lost in my poor use of brevity. What Jgmo says about being under warranty is a major consideration and you should stick to a decent quality mineral oil as per Honda recommendations so as not to jeopardise that. A warranty is worth its weight in gold if you ever need to fall back on it (well at least it's weight in outboards).

Im in agreement 100% with chawk and jgmo for your application you should use a good quality (reputable brand) mineral oil that meets Honda API spec.

Is it really worth the $12.00 total that you will save not to buy the OEM oil from Honda.

Wow... You all make great sense. Dockside, no offense, but the trip to my "local Honda dealer", considering my time, makes it well worth stopping at a car parts store on my way home from work and buying GOOD QUALITY oil, makes it a moot point.
As for the others of you, I understand. The cost difference between syn and mineral, since I'm not trying to "extend" the time between changes, makes it a no-brainer. I always change my oil AT LEAST annually, typically more often. I'm averaging about 50 hours a year, so I feel good continuing to use a quality mineral based oil.
As for the warranty issue, FULL DISCLOSURE..... If you look on the forum for a discussion about submerging 2 BF115s, that's me..... I'm on the road to getting everything taken care of as we speak. I thank God that I thought quickly enough to treat the engines properly after I pulled the boat out of the water. So far, other than my time and 3 oil changes (w/ filter!), it looks like I may get out with only having to rebuild the voltage regulators on the alternators. Both engines were able to be run within 8 hours after being removed from the water. I guess my 35+ years as a licensed aircraft mechanic has served me fairly well.
I really appreciate all the great information that you wise gentlemen (and ladies) are providing. THANK YOU!!
Jim Murray