[Britboy]

I have a 1990 Yamaha Waverunner LX. 650
I have been running a 50:1 mix (premix), using Pennzoil Marine TC-W3.
Have run 2 tanks , no problems.
Can anyone tell me if this oil will be allright for the ski in the long run.
My buddy just blew his Seadoo motor using this same oil, (non pre mix):dunno:

 

[YamaDoo]

Hard to say but it should OK for your Yami. The SeaDoo 2 strokes require better quality oil than the Japanese engines because they were pushed to the limit from the factory. They basically squeezed the same amount of power from a 2 cylinder as Yamaha or Kawi did from their 3 cylinder units.