I have a 2005 yamaha 4 stroke 25hp tiller and we were having problems with it starting (still am)… and so we checked the oil and noticed it was low. I have only had the boat for less than a year and havent changed the oil in a while, so i went to the local marina and asked what oil to use. He picked out a Havoline 10w-30 motor oil, and said that was the stuff. We then put it in the engine and after doing it a buddy of mine told me that we shouldnt have done that. So my question is do i need to pump this stuff out asap or is it ok? The boat hasnt run with this oil in. The oil wasnt the problem, so the next thing to check is the spark plug i guess.
Found on yamahaoutboards.com: May I use Automotive Oils in my four-stroke Yamaha Outboard?
No. Automotive oils are not designed for the operating conditions four-stroke outboard motors face, particularly moisture, cooler operating temperatures, and extended full-throttle operation under load. Oils for your car do not contain, for example, sufficient quantities of the superior rust and corrosion-resistant additives found in quality FC-W oil. Oil with the FC-W rating from the NMMA has been specifically formulated for the tough marine environment. Yamalube 4-M FC-W meets or exceeds all FC-W requirements.
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I was interested in this question and asked a friend who has a Yamaha 4 Stroke with 2000 hours on it. He said other than the Yamaha oil that was in it when he bought it new, his motor has never had anything but Castrol or Penzoil (Non synthetic or Non Blend), whichever he could get cheaper
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Zinc/phosphate (zinc-dialkyl-dithiophosphate or ZDDP), boron (boron nitride), and molybdenum (organic trinuclear molybdenum) all work together as boundary lubricants. Under high temperature and pressure, they form a very hard coating on metal parts and provide protection at startup and under operating condition where the oil film becomes too thin. Moly and BN also reduce friction.
The ratio of these additives has to be carefully balanced for optimal results. But any oil that is formulated with all 3 is a high performance oil that is designed for racing or flat tappet engines.
Calcium (as calcium hydroxide) is one of the bases that are used to form salts any of several organic acids that are used as detergents in motor oil. Some formulations use magnesium or sodium instead of calcium. While these metals are not themselves detergents, they indicate the level of detergent in the oil. Anything over 2000 ppm indicates an oil that is formulated to hold up for a long time.
By this criteria, Yamalube 4M is a very robust oil.
Diesel oils have been used for a long time with good results in marine inboard engines. Most all should be able to meet most if not all of the FC-W test criteria for outboard oil. But just like the newer automotive oils, the latest versions of diesel oils are also showing up with reduced zinc and phosphate content in order to meet new emission standards. The latest diesel oils also have higher levels of ashless detergents in order to keep soot particles in suspension. These don’t show up in oil analysis because they don’t contain metals. They don’t provide much value for gasoline engines and they reduce the amount of some other additives that can be used in the oil because of solubility issues. So I’m starting to be less sure of the newer diesel oils for outboards.
The point is that automotive and diesel oils are designed for different applications than 4 stroke outboards. Using them will not result in immediate engine problems. But they might well reduce the lif
the oil isnt the issue when it comes to outboards
its the additives
Yamaha doesnt make oil
it buys in bulk from someone else then formulates its additives to best work in its motors
biggest issue is the downtime anticorrosion additives