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  1. #11
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,732

    Default Re: Choosing two stroke oil for outboard

    Quote Originally Posted by Oletimer View Post
    So, if I understand you correctly, I can switch 'Smokey Joe' onto a cleaner burning mix? But would it still need 10:1 or do you think that could be eased out to say 20:1 or less?
    Cheers
    George
    That is probably true but even at 20:1, if that were possible, it might well smoke and would be pretty expensive. You could try with a semi-synthetic first.
    Answers to some technical queries at new website http://coxeng.co.uk

  2. #12
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    43,351

    Default Re: Choosing two stroke oil for outboard

    Quote Originally Posted by Oletimer View Post
    So, if I understand you correctly, I can switch 'Smokey Joe' onto a cleaner burning mix? But would it still need 10:1 or do you think that could be eased out to say 20:1 or less?
    Cheers
    George
    You can modify a Seagull post 1967 to run on 25:1 fuel mix by changing the needle ( Villiers carb) or Jets ( Amal carb) and re-tuning. Not advisable for earlier engines due to different crankshaft bearings.
    No mod required for Bing carbs
    All engines post Jan 1978 use 25:1 anyway.

    Full details on John Williams' "Saving old Seagulls" site. Needles / jets available from him too

    EDIT
    It will smoke much less on TC-W3 than it will on a mineral " engine oil" ........ The recommended oil nowadays is TC-W3
    If it is of an age that can also be converted to a 25:1 mix there will be very little smoke .

    Unburnt oil goes out with the exhaust gases, polluting the water
    Last edited by VicS; 14-06-19 at 13:13.

  3. #13
    Join Date
    Jun 2005
    Location
    Solent, UK
    Posts
    4,607

    Red face Re: Choosing two stroke oil for outboard

    It will depend largely on the age of your outboard.

    Older powerheads (smokey Joe is ancient) were manufactured with wider tolerances on dimensions. Modern high power 2-stoke engines need synthetic oils to cling to the bearing surfaces and lubricate despite the higher temperatures and pressures. Mineral oil is perfect for older, engines. The seagulls were originally designed to run on SAE30 single grade engine oil; not even a proper 2-stroke oil.

    My old Yamaha 4 ran on 30:1. My current Tohatsu 3.5 is happy with 50:1 neither was/is particularly smokey. I still use mineral oil in both. If I had a race tuned 2-stroke outboard I'd be using synthetics. I use less than a gallon of petroil a year.
    Grow old disgracefully, it's more fun

  4. #14
    Join Date
    Sep 2018
    Location
    Wolverhampton, UK Boat: Gosport
    Posts
    118

    Default Re: Choosing two stroke oil for outboard

    Quote Originally Posted by Topcat47 View Post
    It will depend largely on the age of your outboard.

    Older powerheads (smokey Joe is ancient) were manufactured with wider tolerances on dimensions. Modern high power 2-stoke engines need synthetic oils to cling to the bearing surfaces and lubricate despite the higher temperatures and pressures. Mineral oil is perfect for older, engines. The seagulls were originally designed to run on SAE30 single grade engine oil; not even a proper 2-stroke oil.

    My old Yamaha 4 ran on 30:1. My current Tohatsu 3.5 is happy with 50:1 neither was/is particularly smokey. I still use mineral oil in both. If I had a race tuned 2-stroke outboard I'd be using synthetics. I use less than a gallon of petroil a year.
    That's interesting, my pair of Seagulls are '67 and'68 (I think), both done enough work to retire but both run as old Seagulls do, just keep plodding along. I've wandered for a while about possibly thinning down the oil ratio, but, accepting the blue smoke trail they go well. An old boy, who has quite a few years with these little motors, was quite adamant about the reliability of the mark being built in in the way they were designed to operate - he wouldn't listen to arguments for the designers simple lack of today's knowledge regarding oil spec or qualities. I'll look into what might be possible.
    cheers
    George
    Last edited by Oletimer; 15-06-19 at 02:31.

  5. #15
    Join Date
    May 2019
    Posts
    21

    Default Re: Choosing two stroke oil for outboard

    If anyone wants to buy in bulk I buy Fuchs marine comp TCW3 oil from Opie Oils.
    A box of 4 so 20L is around £95 delivered.
    It's a good oil.

  6. #16
    Join Date
    Mar 2017
    Location
    Me; Nth County Dublin, Boat;Malahide
    Posts
    753

    Default Re: Choosing two stroke oil for outboard

    IMHO the stuff I use in my strimmer is suitable for the 10 years+ Honda 2.3hp that I attach to my tender. No problems so far.

  7. #17
    Join Date
    Jun 2019
    Posts
    13

    Default Re: Choosing two stroke oil for outboard

    Quote Originally Posted by Oletimer View Post
    I have 2 outboards with very different requirements:
    Tohatsu 9.8 runs well with very little smoke @ 50:1 = Quicksilver


    Question:
    I've been told that fully synthetic oil doesn't burn (as in lubricating 2 stroke engines) so how does it get used in outboards?
    I thought the whole idea was to burn the oil/mix as part of the lubrication cycle, without which you'd have an exhaust full of unburnt oil - or am I mistaken?
    The burning of the oil is after its done its lub. function and that's only because its mixed with the petrol. You should not really run any older design of engine on modern synthetics. Hence the sale of classic oil for classic vehicles.
    As an aside there are "wet sump" 2 strokes which don't burn the oil at all. (unless worn out)

  8. #18
    Join Date
    Jun 2005
    Location
    Solent, UK
    Posts
    4,607

    Default Re: Choosing two stroke oil for outboard

    Before the advent of "specialist" 2-stroke oils, 2-strokes relied upon the imperfect mixing of standard mineral oils and petrol and to ensure an adequate supply to bearing surfaces, excess oil was added to the petrol, 2T oils were developed to mix well with petrol and their better ability to be carried around the bearing surfaces allowed the petrol/oil ratio to be reduced, from 16:1 to 25:1 around the late 50's early 60's. A lot of engine development occurred between then and the 80's when synthetic and semi synthetic oils were introduced. Smaller manufacturing tolerances on bearing surfaces meant the the oils have to withstand higher bearing pressures while adhering the the bearing surfaces. Synthetrics have stronger long chain molecules than mineral oils but are also lighter. These properties are irrelevant to older design 2-strokes.
    Grow old disgracefully, it's more fun

  9. #19
    Join Date
    May 2007
    Posts
    36,816

    Default Re: Choosing two stroke oil for outboard

    Quote Originally Posted by Spirit (of Glenans) View Post
    IMHO the stuff I use in my strimmer is suitable for the 10 years+ Honda 2.3hp that I attach to my tender. No problems so far.
    Aren't hon-duh engines 4 stroke?

  10. #20
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    43,351

    Default Re: Choosing two stroke oil for outboard

    Quote Originally Posted by lw395 View Post
    Aren't hon-duh engines 4 stroke?
    So are strimmers.... except the 2 stroke ones ................ and the electric ones

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