That is because Merc doesn't sell it. I have hundreds of hours on multiple marine engines using Mobil 1 15W50. Not one oil related problem.

I could believe that! That's why I posted a similiar question here: http://www.offshoreonly.com/forums/s...d.php?t=174852

luckily i was able to source sell helix ultra 15w-50 fully synthetic....will do the oil change tomorrow...

Don't run anything 0w, why is that Ray? I'm gonna ask a question to all of you here and see who knows what they are talking about......What does the w stand for, such as
20"w"-50?

weight

It stands for winter, this does not however mean I know what I'm talking about. It means I know the answer to a syupid trivia question.

If I lived in the Great White North I would use a 0w something.
0w oils work very well in extreme cold.
All the w means is that the oil meets a particular spec at 0 degrees F.
The second number after the w means the oil meets a particular spec at 210F.
It's the second number I would be concerned about not the first.
Remember all oils thin with heat, the thickest your oils going to be is when you first start the engine, after that it is all down hill, you oil will get thinner. A multi-vis thins less than a straight weight.
I am not a fan of thin oils in a boat. You are not using the boat in those cold temps, where a thin oil is a benifit, the water's a little hard.
Ken

I put mobile 1 15/50 synthetic in my 496 whippled 800 hp motors after a hard run oil pressure gets low 8psi ,No problems with convetional oil I use 20 w 50 pennsoil changed every month

Thats funny how you just call it a stupid trivia question Hillbilly24, because 95% of people on here, I bet, don't know that answer, they answer just like the other guy, and say it stands for "weight", in reality it stands for winter, and cold pour point. It has absolutely nothing to do with protection rating when heated and at full load. All it means is that the lower the first number, the colder the pour point, therefore, the quicker to the top end of the motor. So, whether or not it is a 0w, 5w, 10w, 15w, 20w, it really doesn't matter. The second number is what you should be concerned with. It should be a minimum of 40, up to 50. It also doesn't matter whether or not its a straight weight oil or multi viscosity. A straight weight will not get the top end as quickly as a multi, therefore actually causing more wear internally.

Also, people that are so concerned with oil pressure, you need to relax. Basically, as long as you have oil pressure, the motor is fine. Think of it as a "garden hose", if you hold your thumb over the end of the hose, it will create more pressure therefore more strain on hoses and pumps, if you let your thumb off, it flows nice and steadily, just like synthetics, they flow more steadily and don't create a whole lot of pressure, they just flow better. That is just one reason synthetics and multi viscosities are better for "ANY" motor, not just marine.

Welcome. You will be better received not being so condescending to the forum population.