This is frustrating. What does it take to get an informative response on this forum?

Try patience first .. also experts have a weekend ..

Sorry for being impatient, but I gotta a motor waiting on some answers and the right oil- and fishing is on hold until I get it running and I was hoping to go out on the water tomorrow and I don't want to waste two quarts of the wrong oil by being hasty...

So, I think I will try the 20W-50 and see how it does tomorrow. Now as to which brand? I have Mobil and Lucas and Yahama available close by...

I don't think you talked to Yamaha.
I think you talked to a parts guy.
Yamalube is not made in a 20w-50.
Go buy a couple qts of Yamaha 10w-30 4-m or any 10-w30 oil labeled FC-W.
go play.
why would only the state of FL need a special oil?

you think that water cooled tiny mite runs hotter in FL as opposed to say LA,MS,AL,TX, or even here in NC.

Why would Florida need a different oil? Precisely why I posted this question here.

And you are amazingly right on target with who said what. I walked into a central Florida Yamaha dealer parts center with the repair shop right out the back door, and it was indeed the parts guy across the counter who said that Yamaha now recommends 20W-50 for Florida four strokers and I asked the guy "do you work on Yamaha outboards" and he said "yes." He had come to counter from the repair shop out back.

And, I agree, I don't think I talked to "Yamaha" either. I talked to someone who is a dealer-representative of the Yamaha brand of outboard motors. He was even wearing what appeared to be an official Yamaha uniform type of shirt. So I figure he should have somewhat of a good idea of what he is talking about which is precisely why I wanted to double check what he told me with what ya'll might have to say around here.

While I was in the Yamaha parts store/repair shop I did notice they had some type of Yamaha oil by the quart that was a 20W-50 and I almost purchased some but at $11.00 per quart I thought I would wait and see if I could beat that price elsewhere.

As to your question:

"you think that water cooled tiny mite runs hotter in FL as opposed to say LA,MS,AL,TX, or even here in NC."

I'd have to say I honestly don't know, tho' I would suspect not, but I am no expert and simply going by what an official Yamaha representative told me that "Yamaha now recommends 20W-50 for all of Florida's four stroke outboards."

I'd like to add that my original question still has not been answered. And I agree with you about using the recommended oil weights and have had no problems with them so far. And I will take your advice and "go play" tomorrow weather be willing.

And on Monday I am going back that Yamaha dealer to double check on what I was told there and see if I can get to the bottom of this matter and double check on the quarts of 20W-50 I saw and will report back when I know more.

Thanks for the responses. I just want to be thorough on maintenance issues.

I work for a Yamaha dealership.
I wear shirts and hats that read Yamaha Master Technician.
I passed the master tech exam in march of 2006.
I receive monthly tech bullitens and updates on a monthly basis.
I have yet to see a bulliten on Florida used 4 strokes.

back in the day, before the nasty divorce.
Mercury marine and Yamaha marine had some joint venture stuff in the 4 stroke line.
the F25 and F40 were a merc design while the F115,F200 and F225 were Yamaha design.

this went on until the nasty divorce about 03 and the last of the J/V stuff was about 05.


your F25 was actually manufactured by mercury,its simply painted Yamaha silver blue instead of mercury phantom black.

it will be perfectly happy with any 10w-30 or 10w-40 oils that carry the marine FCW rating on the bottle.

in fact when that motor was made the FCW rating did not yet exist.

no need for expensive synthetics , regular dinosaur oils work just fine.

Yamaha does have a consumer hotline that will put you on the phone with a corperate Yamaha employee.

Thanks for the response, so basically that guy was full of it and should not have been saying what he did to me. Guess I will stay with the 10W-40 after all since I have not had any issues with it.

And now you went and broke my heart. And I thought I had a yammy. Looks like I will have to sell the boat and all- and go buy a bigger boat with a real yammy on it. Who knows, if Mercs run as good as my merc-yammy I just might be persuaded to switch up.

I hope you are happier now after the nasty divorce! More freedom to fish!

Rodbolt is correct - My 2004 F90 owner's manual states the following

API SAE Motor Oil - Rated SE, SF, SG, SH, SJ 10W-30 or 10W-40.


There is nothing said about not using synthetic oil and back in 2004 synthetic oil was just as popular as it is now.....and Yamaha didn't have their overpriced Yamalube stuff out yet!

I have over 500 hours on my F90 and I've used Pennzoil Platinum Full synthetic 10w-30 since it has had 10 hours on it. Never a problem.

Now i do run the Yamaha Ring Free in my motor right before my oil changes to clean her out.

the nasty divorce was the dissolution of the Yamaha/mercury partnership back about 03.
merc sued Yamaha and lost.

while a synthetic oil may be ok, why spend the money?

newer oils will have an FC-W rating.
stands for Four Cycle Water cooled.

Back in 2008 Yamaha came out with a bulletin describing their latest (4th generation) formula oil for 4-stroke outboards including a new 20W-40 grade.

The Florida and southern area factory reps recommended the 20W-40 due to the warmer water temps and engine temps that are encountered in those parts of the country. It was only a recommendation and not mandatory.

You are right about the 2008 bulletin. I just searched for it and found this:

YamaLube 4M 4-Stroke Oil 1 case Quarts (Northern) - LUB-4STRK-4M-01

"NOTE: Yamaha now recommends 20w-40 for Southern boat users only and 10w-30 for Northern users."

Yamalube 4-Stroke Marine Oil (4M) Quart-1 20w-40 (southern) -LUB-4STRK-4M-01

and what's funny as heck.
you could run a straight 30 wt non detergent and run just fine.

to much ballyhoo about oils yet no one is mentioning the MAJOR killer of ALL outboards.

the COOLING system maintenance.

kinda like the difference on an MPI 5.7L GM stern drive.
for years if it was painted red only 30wt synthetic, same block painted black no synthetic only 25W-40.
painted corperate blue 10w-30 was fine.

there again, painted red or black, the biggest killer of stern drives????
cooling system failures.

I agree with you about the cooling system maintenance, but I am trying to get to the bottom of the oil issue and I think I am just about bottoming out on it now and am looking forward to Monday to see what that dealer has to say about it- as well as check their price on oil. Right now I am at 5.99 per quart or a case of 4 one-gallon jugs at $80.00, or 5.00 per quart.

As for the straight weight oil, I have read a somewhere that Yamaha does not recommend a straight weight (in my 4-stroke outboard) because on start up where most of the wear happens a straight weight takes longer to move up to the moving parts and they recommend a 10w or 20w multi-weight to have a thinner oil move up faster to those moving parts before startup or at startup.

And not sure where I read this, but someone said something about killing the ignition for about the first 10 seconds of engine turnover just to get the oil up to those moving parts before firing it up. Not sure if that is really a benefit, tho' some slick-dry oil additives might help along with those adhesion additives just to make those dry additives (and oil) stick to the metal walls better to lessen the wear on start up while they are moving and waiting for the oil to move in.

At this point I am thinking that maybe the "best" choice for oil would be to follow the updated recommendation from Yamaha and go with a 20W-40 oil, even tho' my motor and manual call for a 10w-30 (cooler weather) and 10w-40 in hotter weather.

And from my searches there is not a whole lot of 20W-40 oil choices out there. I can find more 20W-50's tho'... and at this point I am wondering how much of a difference there is between these two if any real noticeable differences???

even Wal-Mart carries the FCW rated oil you need.

given a choice on replacing the water pump and t-stat every 100 hours or yearly or the oil at 200 or everyother year?
Ill take the cooling system mant.