correct engine oil for Honda

Both the owner's and the service manuals specify that any brand of automotive oil displaying the "star symbol" is suitable for use in a Honda outboard.

In reading information on a Yamaha site however, they clearly specify that automotive oil is definitely not suitable for use in their four-stroke outboards and they prominently display this image.

They cite the fact that specifically-designated marine oils contain certain additives that are necessary for use in a marine environment and also that additives prevent foaming of engine oil at high rpms....noting that auto engines do not typically run at 5000 - 6000 rpms for sustained periods of time.

Are the two brands of outboard really all that different when it comes to using an oil that will best protect the motor? As far as I can tell, Honda doesn't sell a specifically-designated marine oil. What to use??

Just my opinion. Not being a mechanical engineer specializing in internal combustion engine lubrication, not real sure what it's worth either. But, here goes:

The Yamalube is "probably" the "best" way to go. Why? Because they do employ mechanical engineers specializing in engine lubing. And, I'm guessing that you would be hard pressed to argue with their science. The oil they recommend probably does contain enhanced corrosion inhibitors that won't be found in most off the shelf automotive engine oils.

The point about the outboards being operated at elevated RPM as compared to your car is another fact that really can't be argued against and if they have a component in their oils which address this "factor" then that would make it a superior choice as well.

I've never purchased any of the Yamalube but I'm betting it costs significantly more than 5w30 Valvoline.
Will the Valvoline work? You bet! Is the Yamalube better? I would think so. But, don't forget the big to do about synthetic oils when they first came out. They seem to be superior in every way and, I believe it's been proven that, when used as directed, they do outperform petroleum based oils pretty much across the spectrum. However, they are much more expensive than "regular" motor oil and many people ruined many engines when using synthetics by not following drain intervals and maintenance procedures due to a misconception that amounted to "I paid more so it should last longer"

There are benefits to be had with the "enhanced" motor oils to be sure. But, with the increased cost of these products, you would need to do some very careful and (I'm guessing) very sophisticated tracking to actually put a dollar amount on the returns. And, it could just turn out to be pennies.

I'll jump in on this, too. Personally, I think synthetics are a waste of time on an outboard. You still need to change the oil every 100 hours, so why waste the money on synthetics. Interms of oil for your Honda outboard - after break in, I believe you can useabout any 10W-30 petroleum-based high detergent oil with an API certification of SG or higher,unless you are operating in extreme conditions. There are probably a 100 ormore brands out there, but there are only about five significant manufacturersin North America. So all those brands areoften the same oil branded for a specific retailer. For example, Toyota motor oil is made by Mobil. Mobil is using their Mobil Clean formula, (not to be confused with Mobil Drive Clean 5000 which is higher priced.) Mobil only packages their Mobil Clean in drums and bulk. Mobil's own literature terms this oil as "a entry level oil." The same Mobil oil is also the Honda factory oil and the GM Goodwrench oil.

I'm not sure whether Honda has any additional specifications on it's oil, butthe Owner's Manual simply states 10W-30 oil with an API certification of SG orhigher.

The key is to change the oil at the recommended 100 hour interval, or everyseason, whichever comes first. If you think about it, if you average 30 MPH onyour engine, then 100 hours is equivalent to 3000 miles. But that 3000 miles usunder rather extreme conditions. It is somewhat equivalent to driving your caror truck, loaded down, up hill, for 3000 miles.

One final issue. I've seen at least one knowledgeable outboard tech say that synthetics may actually be harmful to outboards, especially those that run at low RPM's for extended periods of time. The reason is that the "thinner" molecular structure of synthetics allow more unburnt fuel to get by the rings a low rpm's and cooler engine temps, thus more oil dilution.

For the piece of mind and the minimal extra cost, just purchase Honda oil. That is what I put in all the Honda OB's I service. Then there is no question about compatibility.

All good points so far...thanks, guys. Would be interested to hear what someone who sells both Honda and Yamaha uses....

I have used Castrol GTX in my Honda for 7 years now.
so far so good, only thing i notice is the oil is very black at the 100 hour change.

Best to use " Honda 4 stroke outboard oil "--------------------They certainly are expensive , hard working machines , so why try to save pennies on oil ???

Now that I've looked on the web, I see that a Honda marine 4-stroke oil does indeed exist....no mention in the manual and no dealer has ever offered me anything but regular (automotive) Honda motor oil so this is new news to me! I'll use it if I can find it.

Here's something more on the subject from a very reputable oil refiner. Honda, Yamaha, Mercury and many others tout the NMMA FC-W ratings on the 4 stroke outboard oils that they sell.

http://www.amsoil.com/storefront/wct.aspx

As they explain the NMMA FC-W rating in detail, you might note that the only mention of the American Petroleum Institute (API) rating is on one line of this advertisement. Interesting because NO engine oil goes on the shelf for sale in the United States without the API "donut" on the container while FC-W oils can be hard to find but will always be sold with the API certification listed.

This particular ad is probably a couple of years old because it lists the API rating as SL. There have been two "upgrades" since the release of SL rated oils and the currently available SN rated oil was developed in 2010 for 2011 automotive engines.

The API rating has always been deemed to be "backwards compatible" with all earlier ratings so if your owner's manual calls for an SG rated oil the SL, SM or SN should work just fine. However, I have read that some older engines with flat tappets have not faired well with the newest formulations due to a great reduction of a substance called ZDDP or...ready?...are you sure?... Zinc Diakyle Dithio Phosphate!. ALLLLLrighty then!

So, that kinda sucks! And, it complicates our decisions a bit since, very soon, those new formulas will be the only thing readily available to us lowly consumers. They took that particular "protective" ingredient out of the oils to help save catalytic converters.

Funny, I haven't seen a cat converter on an outboard yet. But, I'm sure they're acomin"!

I've also recently come across some articles about the FC-W rating as being...well...are you ready for this one??? OVERRATED!

That's right! It has been noted that MOST engine oils will pass the "salt mist cabinet" torture test that is used to obtain the NMMA rating but most of the retailers aren't very interested in printing the certification on their containers since it doesn't apply to their target market. Hey! That rhymes! Target Market!

So, please excuse me while I now go and write a Christmas song about slippery reindeer. oily doilies and target markets! Yippee!

I use the Amsoil for 4-stroke outboards. I can absolutely attest that the motor is definitely more quiet with this oil vs the Honda outboard oil.

I think its interesting that even Amsoil recommends the 100hr change interval...


http://www.amsoil.com/storefront/wct.aspx

twin 150 said:

I use the Amsoil for 4-stroke outboards. I can absolutely attest that the motor is definitely more quiet with this oil vs the Honda outboard oil.

I think its interesting that even Amsoil recommends the 100hr change interval...

Service Life​

• Four-stroke outboard motors and personal watercraft applications: Due to potential fuel dilution or water contamination, change oil at the engine or watercraft manufacturer recommended interval.
​

http://www.amsoil.com/storefront/wct.aspx

Click to expand...

Not so sure that it's a good idea to run synthetic in your 4-stroke outboard ?

I can't honestly begin to understand why not.

I figure less friction is better. Plain and simple really.