Paul Yaw wrote:

Paul wrote:

Ken Powell wrote:

     Paul,
     I would like to share some info about 2-stroke oils with everyone.
     This is a pragmatic observation based on 20 years of racing motorcyles
     and 5 years of working as a motorcyle mechanic (BTW, I was working in
     a Suzuki shop in 1975 when the RE5 was introduced. What a beautiful
     motor!)  I am not a petroleum engineer (I'm a programmer) so you can
     take this with a grain of salt.  First of all, note that 2-stroke oils
     are formulated based on the anticipated operating temperature.  I
     would like to break this into 2 groups; water cooled and air cooled
     engines:
     1.  Water cooled engines can use a TCW-III approved oil successfully.
     These oils are widely available from Mercury Marine, OMC and yes, even
     Walmart.  I believe that all of the outboard oils sold by the outboard
     companies are petroleum based and these are much cheaper than synthetic
     oils.
     2.  Air cooled engines run considerably hotter at the upper end of
     their operating range and have a big problem with carbon in the ring
     lands.  Pistons which utilize a dykes ring seem to suffer from this
     more that other designs.  Penzoil makes a petroleum based oil for air
     cooled 2-strokes that is very popular with snowmobiles and Rotax
     2-stroke airplane engines.  However, I rode Maico motorcles for about
     10 years and they used a Mahl piston with a dykes ring.  Ring
     sticking was a constant problem.  I tried many different oils and
     what worked for me was an oil called Golden Spectro - the dykes ring
     did not sieze due to carbon build up.  Conclusions:
     1.  I would use Golden Spectro or Penzoil for air cooled engines on
     a 2-stroke powered airplane.  Golden Spectro mixes at a 40:1 ratio
     in a motorcycle.
     2.  I will use a TCW-III oil in a rotary powered airplane.  I think
     that the oil cooled rotor's temperature will stay within the operating
     temp range of these oils.  At this time I have no preference for a
     particular brand.  Note that a petroleum oil will leave a protective
     film to prevent rust while the synthetics generally run so clean that
     no film is left to prevent rust. While is is true for a recipricating
     engine, I'm not sure if this is applicable to a rotary.
     3.  I believe the synthetic oils are far superior to petroleum based
     oils, but I think this is overkill for our application.  However, you
     could probably mix a synthetic much leaner if carrying the oil was a
     problem due to limited space or payload (or CG).

     Ken Powell

Wow, that's weird.  I just burned some of that TODAY to see what would
happen.  First, I could not get it to burn.  I just dumped some on a
piece of aluminum and hit it with a torch.  It didn't thin much from the
heat, and it finally gummed up a bit and turned brown.  So I heated it
some more and guess what...The brown gum dissapeared.  I mean it just
plain went away, and I was left with a clean piece of aluminum.  I am
not kidding! Try it yourself.  I guess that it didn't burn because the
aluminum was pulling so much heat out of it.  Jim Mederer brought up a
good point about burning these oils to see how much crud they leave
behind.  He was interested in what kind of crud was left behind, not how
much.  His contention was that a lot of slippery goo was better than a
little bit of abrasive ash.  Why didn't I think of that?  My buddy Pat
who was a wholesaler in the motorcycle business for years says that just
about everyone across the country carries it.

PY

 
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