Quote:
Originally Posted by old jupiter
Was surprised to find this old thread revived.
Despite this, the investigation found no significant pollution, no rainbow-colored oil flows anywhere around the lake. My guess when reading about this long ago was that the fuel/oil comprised such light fractions that it mostly evaporated into the air . . . hardly desirable either, but in any case no smoking gun was found (and I forget whether lake sediments were looked at).
|
First post here. Forgive me if I am barging in on this.
The older petroleum premix oils often left less oil film on the water because, as you suggested, they tended to leave the engine as vapor. Modern synthetics leave the engine essentially unchanged. The fact that they don't burn is one reason you can run them up around 100:1.
The synthetics used in modern outboards do leave a film on the water, in part because a 300HP bass boat motor sucks a lot of gas and therefore a lot of oil. I live on a large lake that was once popular on the bass pro tours. One Saturday we went swimming after a big tournament. The water had a noticeable film and so did we when we got out. After that I never went swimming after a holiday or tournament.
Oil injection such as the old Yamalube system was significantly more efficient than premix. I did some testing back in the 70's and found the Yamalube systems typically used oil at about 70:1 to 90:1 at a time when premix was limited to 40:1. The oil pump was connected to the throttle cable to increase oil with fuel consumption. I saw numerous bikes come into our shop with the lube cable disconnected (or broken). They never seized as long as oil was getting to the pump.
Doug