4 Stroke outboard oil

Discussion in 'Gas Engines' started by bmtsa, Sep 5, 2012.

  1. bmtsa
    Joined: Aug 2012
    Posts: 7
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Panama, Rep.

    bmtsa Junior Member

    We are operating a fleet of boats in the tropics. Engines are Yamaha 4 stroke outboard and used heavily (average 3000 hr per year). Until now we have used 20W-50 motor oil. I am thinking of changing to straight SAE 40 oil, a lot less expensive and now I have all the "Local Experts" screaming bloody hell. Although most of the experts have problems reading and writing, I am having second thoughts now about changing to the less expensive oil. Anybody have any input on this subject?:?:
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 489, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The multi grade oils are the only route to go. If you'd like to void your engine warranties, then go ahead and use a single grade. The multi grade oils work over a much higher range of temperatures, which you'll need in the tropics.
     
  3. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Check what kind of oil is used for automobile service in your area. There is normally a small price difference between straight oils (almost extinct) and multi grade, so I guess you are now using synthetic oil and you compare that price with mineral oil.

    Your Yamaha fleet will run happily on mineral 20W-50.
     
  4. Frosty

    Frosty Previous Member

    Multi grade oil is for changes in Temperatures such a winter and summer. Gone are the days of changing viscosity for changes in season.

    My Yanmar 250HP warranty specifically stated on the label on the dip stick that warranty would be void if I used anything but 30w. It was difficult to obtain,--- w 40 being popular .

    Now warranty has expired I use straight 40 as does anyone else.

    Your engines are water cooled and thermostatically controlled . There is no increase in running temperature because of your location.
     
  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 489, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There are three basic reasons to use a multi grade oil.

    The first is at start up. The oil is drained to the bottom of the engine and cold. The first few seconds of a cold (a relative term) start up, produces 90% of the wear in a typical outboard. A mono grade ill be thicker and slower to get to the moving parts, as everything is spinning up. Since the multi grade oil is thinner at low temperatures, it reaches all parts of the engine quicker than a mono grade oil, hence less wear at the time it counts most.

    Multi grade oils produce better fuel economy, by up to 3% - 4%.

    Multi grade oils are thicker at higher temperatures which reduces oil consumption and better protects internals.

    It would be better to understand it this way. A mono grade is a fixed viscosity oil. It's probably fine when you're at operating temperatures, but you'll wear more on start up, have lower fuel efficiency and burn more too.

    The viscosity of an oil changes; dependent on the temperature, the pressure, and the actual shear stress on the oil as a result of flowing between moving components. Even in an outboard with liquid cooling, the oil temperature/stress levels will fluctuate with load and a mono grade isn't as capable of dealing with this as well a multi grade.

    A 10/40 oil for a tropics used outboard would be the wise decision, switching to a 10/50 as the engine's oil pressure begins to drop from wear.
     
  6. jonr
    Joined: Sep 2008
    Posts: 721
    Likes: 11, Points: 0, Legacy Rep: 57
    Location: Great Lakes

    jonr Senior Member

    I'm curious - how many hours do you get before an overhaul is needed?

    Also note that less expensive oil means you can afford to change it more often.
     
  7. gonzo
    Joined: Aug 2002
    Posts: 15,504
    Likes: 1,042, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    For a commercial operation like yours, the cheapest will be to use synthetic oil. It lasts three times longer between changes and lubricates better too.
     
  8. bmtsa
    Joined: Aug 2012
    Posts: 7
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Panama, Rep.

    bmtsa Junior Member

    After appr. 4000 hours we start having problems, mostly with the valves. Most of the time we are just replacing the whole motor, as good mechanics are hard to come by on an Island in Panama, parts are too expensive and hard to obtain. So you may be waiting two months for parts after you deposited the money spending $ 8,000.00 in parts plus the cost of the mechanic. And with a bit of bad luck, which is almost guaranteed around here, you have problems again after a few months. Warranty is basically unknown her. If you buy a brand new engine here the warranty is 6 months or 200 hours, which is equal to two oil changes. We have those in less than three weeks.
    Karl
     
  9. bmtsa
    Joined: Aug 2012
    Posts: 7
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Panama, Rep.

    bmtsa Junior Member

    Thanks for your detailed reply. You certainly made your point with having most of the wear at starting of the motor.
    I will have to bite the bullet and toss that expensive oil two times a month.
     
  10. bmtsa
    Joined: Aug 2012
    Posts: 7
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Panama, Rep.

    bmtsa Junior Member

    In twelve years of business and having spent hundreds of thousands of Dollars with the one and only Yamaha Rep, I have never had anything covered by warranty. 6 months or 200 hrs warranty expires in my case in less than 3 weeks. Actually, I am considering going back to the 2 strokes as they are about half the price, last about the same time and anyone around here can repair them.
     
  11. bmtsa
    Joined: Aug 2012
    Posts: 7
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Panama, Rep.

    bmtsa Junior Member

    Thanks for your detailed reply. You certainly made your point with having most of the wear at starting of the motor.
    I will have to bite the bullet and toss that expensive oil two times a month on every boat.
     
  12. jonr
    Joined: Sep 2008
    Posts: 721
    Likes: 11, Points: 0, Legacy Rep: 57
    Location: Great Lakes

    jonr Senior Member

    I would consider buying slightly larger engines and running them at lower output (about 80% load and rpm as low as will get the job done). It might also be worth it to ship them back to the US for a high quality overhaul.

    Single weight oil has more oil in it and fewer additives to form deposits. It is also thicker at ambient, so more of it sticks to everything which helps for corrosion and on startup. Overall, I (and people who have done lots of testing) consider it a wash unless there is below freezing weather involved. But you could certainly run 1/2 the fleet on each and do your own test.
     
  13. Frosty

    Frosty Previous Member

    Most of the wear is at start up on every engine regardless of location temps or oil viscosity.

    As Transport /fleet manager for Sealand shipping co in the middle east I changed 100s of gallons per week In that climate I used w40 on EVERTHING .

    Jonr is correct the more you mess with oil by using additives the less oily it is. No engine manufacturer specifically requests a brand of oil just viscosity.

    I even use w 40 instead of Auto Tranny Fluid in Allison automatics. Allison thought it a good idea, and approved it.

    Modern deisel engines with 22.5 compression ration and turbo running at +4000RPM use 40w. Why should a small alluminium light weight engine of 150Hp at half the comp ration need better.

    I never recommend oils, just give reasons for my choice.

    Harleys use a nasty little market plan to make you buy special Harley oil. They insist on 60w --of course it is not a normal viscosity so you buy from Harley at exorbitant prices.

    They actually run quite well on 40w and why should they not. Synthetics is like feeding strawberries to pigs.

    Synthetics are for Formula 1 that have extreme stress and short engine life. Unless you want to use it on your cement mixer , there is no law against it ......
     
  14. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 489, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    If you don't think viscosity at start up is important than you just haven't looked at the test data. This is the whole point of a multi grade, low viscosity at start up, so it gets to the parts faster and higher viscosity once the engine is hot, so it stays stuck to the parts. If you want to old school your way through life that's fine, but the data is pretty clear.

    Lastly, outboards are highly stressed engines, in most cases. Just take a look at the engineering and compare the displacements to the output ratios. They're screaming little beasts and quite highly stressed, especially in the tropics. You can get away with single grades in a lawn mower engine, but tighten up the build and output tolerances, like that in an outboard and oil is just cheap insurance. For a fleet of rentals, I'd agree with Gonzo and go synthetic, just because you can leave it in longer, but the added cost of a synthetic usually doesn't get covered in the lengthened oil change interval.

    If it was my fleet, I'd "Z-Max" each engine just after break in, than regular oil changes until 2,000 - 2,500 hours, then Z-Max again.
     

  15. Frosty

    Frosty Previous Member

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.