Gasoline in an outboard

Discussion in 'Bubba's Outboards' started by Bubbakat, Aug 22, 2006.

  1. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    This is some interesting stuff I read about todays gasoline in out board engines. This is by no means my work just some copy and paste. Interesting non the less.


    I use 87 octane in my car, why can't I use it in my outboard?
    This stuffs' not fit to use in your lawn mower, let alone a $12,000 high performance outboard motor. The low octane and lack of detergent additives just leave you open to motor failures from detonation, gum and carbon formation, coked up rings and piston scuffing. Your automotive engine is a 4 stroke with totally different lubrication and fuel usage requirements.

    Can I use oxygenated gasoline in my boat?
    A major oil company survey of the manufacturers of engines for non-automotive uses -- boats, garden tools, chain saws and snowmobiles -- indicates that oxygenated gasoline will perform satisfactorily in most later-model engines. However, some manufacturers expressed concerns about its use in older engines. The owner's manual is the most authoritative source of information about the fuel requirements of your equipment. If your equipment is older and the manual does not mention oxygenated gasoline, consult an authorized dealer.

    Oxygenated gasoline will perform satisfactorily in most engines under normal conditions of storage and use. However, you should be aware of the potential problems -- two involving the gasoline itself and several involving gasoline/equipment interactions. Follow the suggested precautions if they apply to your situation.

    Concerns are:

    Phase Separation
    Gasoline oxygenated with alcohol readily takes up water when it is present. The water may be condensed out of humid air or be a contaminant in the fuel system. Dissolved water will not interfere with engine operation. But if enough water is present, gasoline oxygenated with alcohol will separate into two liquid phases: a top phase which is almost all gasoline (and oil, in the case of 2-cycle fuel) and a bottom phase of water and alcohol. (Phase separation is not a problem with gasoline oxygenated with MTBE.) Phase separation may make the engine difficult or impossible to start. To solve the problem, replace the separated mixture with fresh gasoline.

    The situation with the greatest potential for damage is phase separation in the fuel tank of a 2-cycle engine without an oil sump. If the engine is able to start and run on the alcohol/water phase, it won't be lubricated -- almost all the added engine oil will be in the gasoline phase.

    To minimize the chance of phase separation, keep water out of your equipment's fuel system and practice good fuel management. You can eliminate the possibility of water pickup when your equipment is not in use if you keep the fuel tank full and close the tank vent.

    Deterioration During Storage
    If a gasoline is of poor quality or if the storage conditions are adverse, gasoline can oxidize and form gums over the period of several months. These changes can increase engine deposits and filter plugging. There are reasons to suspect that oxygenated gasoline may form gums more readily than conventional gasoline, but actual evidence is limited. A safeguard recommended by some manufacturers is the use of name-brand gasoline from companies recognized for the quality of their products. Another safeguard is good fuel management.

    Practice Good Fuel Management
    Match your purchases to your consumption.
    Don't buy more than you'll use in one to two months.
    Store gasoline in a tightly-closed container in a cool, dry place.
    Leaning Effect
    Compared to a conventional gasoline, oxygenated gasoline results in a leaner air-fuel mixture. This causes some engines to run rough. Also, engines may run hotter on lean mixtures, which, in the extreme, can result in engine damage. If the engine in your equipment is running rough and it has an adjustable carburetor, check that the adjustment is proper for the fuel you are using. Either contact a knowledgeable serviceman or follow the manufacturer's instructions in your owner's manual.

    Some manufacturers--Arctco, Bombardier, Outboard Marine, and Polaris--indicate that certain of their engines may require larger carburetor jets to compensate for the leaning effect of oxygenated gasoline. Consult your authorized dealer or serviceman about the manufacturer's recommendations for your engine model and year.

    Vapor Lock And Difficulty Restarting A Hot Engine
    "Vapor lock" is loss of power or engine shutdown due to gasoline vaporization in the fuel system. Vaporization prevents the fuel pump from delivering sufficient gasoline to the engine. Factors favoring vapor lock are high ambient temperatures which accompany high power output. Sometimes vaporization occurs after the engine has been intentionally stopped because of the cessation of mechanical cooling and fuel flow. In this case, the hot engine will be difficult to start.

    Vapor lock and hot restarting have been reoccurring problems for engine manufacturers. Some manufacturers are concerned that oxygenated gasoline will aggravate these problems because adding either ethanol or MTBE to gasoline increases volatility.

    The volatility of gasoline sold in each area of the country is tailored for the expected ambient temperature range. Buying smaller amounts of gasoline more frequently make it more likely you will have a gasoline of the correct volatility.

    Your owner's manual may suggest additional ways to avoid vapor lock. Remember that some situations lead to vapor lock more often than others. One is running an engine at full power for an extended time on an unseasonably warm day. If vapor lock does occur, it will probably be necessary to allow the engine to cool before it can be restarted.

    Materials Compatibility
    Deterioration of elastomers and plastic parts is not expected to be a problem with current production engines. For older engines, some problems have occurred with elastomeric parts (fuel pump diaphragms, needle valve tips and seats, fuel lines, gaskets, etc.) when they were first exposed to oxygenated gasoline. Some manufacturers recommend that you frequently inspect the fuel system for leaks and for deteriorating elastomeric parts when you operate an older engine on oxygenated gasoline. There is also the possibility of leaks after you change back to conventional gasoline: Seals that were swelled by oxygenated gasoline may shrink. (The same mechanism is responsible for leaks cause by large changes in the composition of conventional gasoline.) Replacement fuel system parts have been engineered to be compatible with oxygenated gasoline.

    Metal Corrosion
    Some manufacturers report corrosion of metallic fuel system parts when gasoline oxygenated with alcohol was used in older engines. Except for periods of prolonged storage, this does not appear to be a concern with late model engines. Corrosion problems may be aggravated by the phase separation of a gasoline oxygenated with alcohol. The alcohol/water phase tends to be more corrosive than the oxygenated gasoline itself.

    Solvency
    Oxygenated gasoline may loosen deposits from fuel system surfaces because it is a better solvent than conventional gasoline. The suspended solids can plug the fuel filter and carburetor passages. This is not a common problem. It is most likely to occur when older equipment is first fueled with an oxygenated gasoline. Clean the fuel tank and fuel system and replace the fuel filter; then refuel with fresh fuel.

    What Octane gasoline should I use for my outboard?
    I have an older outboard with higher compression. Should I burn PREMIUM gas?
    NO! here's why. The octane ratings are composed of 2 components, research octane and motor octane (RXM/2) divided by 2. The RESEARCH octane is the quality of the base stock, the MOTOR octane is derived from additives. The oil company will never tell you the ratios. Problem is the highest octanes are achieved by MOTOR octane additives, which will just gum up the pistons in a 2 cycle engine. Base stock is generally the same. The MID-GRADE gas has the detergent additives needed to clean your motor and sufficient octane for MOST motors. If you have a MERCURY, FORCE or OMC motor from the early 70's thru mid-80's refer to technical bulletins from the manufacturers for timing changes and replacement head gaskets to lower compression to use today's gasoline.
     
  2. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Great post Bubbakat, but I only understood about 10% of it. LOL
     

  3. fishhook

    fishhook New Member

    Messages:
    658
    State:
    Willow Woo
    Good post, we talked about this in a previous post were a lot of you said that if you could burn it in your car you could burn it in your boat motor. Talking about the low octaine gas most people don't look at what it does to the motor, only to what it does to their wallet.
     
  4. badkarma

    badkarma New Member

    Messages:
    772
    State:
    Oxford,Miss
    I'm sorry but I think most of that is bull.I have a 1973 20hp Merc that runs good and always has and my 93 Johnson runs good too.
     
  5. Little Mac

    Little Mac Active Member

    Messages:
    1,828
    State:
    NW Arkansa
    I accidentally put 87 octane in Topsgtlawrences Boat one time and it plain wouldnt run, I didnt know any better at the time. couldn't a person put an octane booster in the 87 octane? I don't know thats why i am asking.
     
  6. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Mac you most likely could put an octane booster in it and it would suffice but by the time you bought the booster and added it to the already high cost it would be more cost affective to go ahead and get the mid range.
     
  7. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill



    John I knew it was one of the guys on here that had brought this up and I dismissed it as I had been taught for years that the 87 octane was as good as it gets then after reading this and some more atricles I found I am going to try the mid grade fuel in mine and see what takes place.

    To you I do think I owe you an apology.
     
  8. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Food for thought on octane;

    What does a higher octane do?

    Using lower octane and why?

    What does a 2 stroke need to function reliably?

    I'll argue the points after some more posts.
     
  9. blackwaterkatz

    blackwaterkatz Active Member

    Messages:
    3,659
    State:
    Andrews, SC
    I don't know the source of the info posted, bubbakat, and I'm not qualified to analyze the information. The owner's manual for my 90hp yammie 2-stroke specifically says it is designed to run 87 octane, and it seems to run just fine. I do use stabil and occasionally will add some sea foam. The dealer told me not to run high octane because it didn't have the additives needed to keep the engine clean, etc. He didn't recommend using mid-octane, or not using it.
    Does anyone have experience with higher octane use in this engine? I realize that some engines may need higher octane to prevent spark knock, but why pay more if the lower test will do?
    Excellent topic for discussion, btw....
     
  10. zappaf19

    zappaf19 New Member

    Messages:
    1,574
    State:
    Monticello,IN
    Willard I have a old Merc tower of power. What grade would use in it?
    Bill
     
  11. fishhook

    fishhook New Member

    Messages:
    658
    State:
    Willow Woo
    Most motor instructions I've seen has a minimum of 87 octane. I have a 1994 90 horse Johnson which says that and also says to use the higher octane for max horsepower and cleaner burning. The higher octane gas burns slower which leaves less carbon deposits on pistons and plugs. Most two cycle engine makers now have a tag on the gas tank or a sticker on the motor telling you to use the higher octane gas or it will void your warranty and thats do to carbon build up under and around the rings on the piston which leads to premature failure. The higher octane gas also has more dispersants where the oil will mix better and not seperate like in the lower octane gas. To me the higher octane gas would be cheaper to use in the long run offsetting the cost of tuneups and maintenance. I use it in every gas powered piece of equipment I own which is quite a few and I also use Stabil every time I add gas because I don't at the time know just how long it will set before I use it again.
     
  12. ShilohRed

    ShilohRed New Member

    Messages:
    4,339
    State:
    West Tn
    WOW and to think I have been using the wrong gas for 35 years..
    I run the 87 in every motor I have and ever had. You know when I was hauling oil. I loaded out next to the guys that were hauling gas.
    9000 gallons were dumped in the tank all from the same hose. Then they would dump 5 gallons of mix in the mid grade and the premium that was all that made it anything then 87 grade.
    Also I know if a store is about out of premium and the truck comes in with 87 it gets dumped into the premium tank. I know its not legal. but happens all the time.
    2005 Suzuki 140 states 87 on it.,


    Pete
     
  13. ShilohRed

    ShilohRed New Member

    Messages:
    4,339
    State:
    West Tn
    Also Willard thinks for posting that.
    If I remember right that came out after all the OMC motors were blowing up. You know the ones that put them under that time.

    Pete
     
  14. fishhook

    fishhook New Member

    Messages:
    658
    State:
    Willow Woo
    The difference in grades of gas is not just an additive, its a whole refining process. What they add to the gas is the color and if you ever tried a higher octane gas in all those motors you would see just how much difference there is. They would run smoother and have more power on a hill or towing. If you have always run 87 octane gas then you should know that lower octane gas will ping on a hard pull and over time it will make your motor harder to start plus diesel sometimes when shut off and tune up more often do to carbon. I'm sure some on here have seen this very problem at one time or another. Its a shame that some one will almost always get on these threads that are just trying to pass along a little information so people can make up their own mind as to what to do or not to do and start making a lot of derogatory and misleading statements to justfy what themselves are doing. Why can't we just thank the man for the information or just add to it, we're suppose to be a brotherhood of fishermen and women helping each other to learn and make new friends.
     
  15. ShilohRed

    ShilohRed New Member

    Messages:
    4,339
    State:
    West Tn
    Sorry but I do not pull hills or tow with my boat. LOL
    Also I sure hope my truck does diesel as its a diesel .
    Yes I know cars will knock. but if the time is set right its not a problem. Never has been.
    Also Sir I see I must have picked a sore spot with you. And all that I can say is Get a life.
    AS for posting what I did about them loading out of the same tank for all grades . That SIR they sure did and I know some people that still haul today and the same tank is loaded with all three grades just the additive added.

    Also I know Willard and he knows me. AS for people like you its the reason I almost left the BOC.
    So you sir FISHHOOK have a great day, And I for one will just stop posting at all.
    And any other thing for that matter. So have a great day and this is my last post.
    Because of people like you..

    Pete




     
  16. fish

    fish Active Member

    Messages:
    1,573
    State:
    ChattanoogaTenn
    Willard, do you know what is recommended for my 50hp Nissan? That may be my problem with it dropping a cylinder at times and I suspect that may be the reason it won't crank right now. We appreciate the info you posted buddy.

    Pete, I don't see how your motor could run any smoother than it does right now. I believe you could set a glass of water on that motor and it wouldn't vibrate off.
     
  17. Team StrayCats

    Team StrayCats New Member

    Messages:
    244
    State:
    florida
    Hi good post. I have an 83 mariner and was useing reg. unleaded and it ran ok but then moved to unleaded plus and it seems to run a hole lot better. Havent tryed stabil what does it do? Great post
     
  18. fishhook

    fishhook New Member

    Messages:
    658
    State:
    Willow Woo
    If you go to a bulk plant there are 4 hoses they fill from for the three grades of gas plus diesel. The dieselling is not from an incorrect timing, its caused from hot spots formed by carbon deposits in the cyclinder which is left by the slow burning fuel and detonates the fuel that keeps coming into the cylinder after the ignition is turned of and on a hill or hard pull which you said you don't do is caused from the short duration of the fast explosion of low octane fuel rather then a long slow burn of the higher octane fuel. If I hurt your little feelings because you were being a smarta$$ then so be it, there are people leaving the site but I don't believe its from stating facts, I think its because of smarta$$ answers like yours in the different threads when most on here are looking for help or information, those kind of replies should be over in the HI side and I can back what I've said with facts. If I have offended anyone else, please accept my sincere apology. There is a difference between talking trash and joking around but being a smarta$$ is another thing.
     
  19. savage308

    savage308 New Member

    Messages:
    399
    State:
    Victoria, Texas
    Fishook, Sorry to tell you this but you are definately wrong in this instance. Gas and diesel are transported by pipeline here in texas. One pipe is used to transport both unleaded and diesel. Gas/diesel holding tanks hold either one and then as the different haulers pick up the product then the additive is added for Exxon/Shell etc.... Each of the gas stations has their own brand of additive on site and that is pumped into the tanker trailers as they load gas. Valero and Citgo are two of the local companies that supply 100% of our surrounding 100 mile or so area and this is how they get the fuel to the gas stations. It is refined in Corpus Christi and the pipeline goes to houston. They pull out of the pipeline as it's coming by their Million gallon holding tanks. This is just a Fact that I wanted to let you know how it is done if it goes by pipeline.
     
  20. fish

    fish Active Member

    Messages:
    1,573
    State:
    ChattanoogaTenn
    John, Pete and Willard are both personal friends of ours and I can tell you one thing, they both always try to be helpful. You definitely are wrong that Pete is a smarta$$, it looks to me like you were the one to throw the first punch on this one.