01 Merc 25 2 stroke

Discussion in 'Outboard Maintenance' started by devrep, Jul 6, 2015.

  1. devrep

    devrep Well-Known Member

    1,936
    629
    968
    So this is my new old motor. Did some googling around and read that some years they made the blocks out of Mercosil and that those motors should be run at a 40:1 oil ratio. Anything to this and what years would have had Mercosil blocks?
     
  2. HaMm3r

    HaMm3r Well-Known Member

    Supposedly, blocks with Mercosil had serial numbers G202750 and higher. My 1999 25hp was Mercosil so I'd bet your 2001 is too. Always ran 50:1 in it.
     

  3. cutrunner

    cutrunner Cert. Yamaha technician

    A higher quality of oil will make more difference than a 10\1 difference in ratio
     
  4. devrep

    devrep Well-Known Member

    1,936
    629
    968
    Roger. Thanks.
     
  5. RunningOnEmpty

    RunningOnEmpty I Love microskiff.com!

    676
    211
    168
    The older blocks used nikasil chrome plating on the bores. The Mercosil blocks started in 1994 If I remember correctly? I've owned both and always mixed the oil at 50:1 without any problems.