On the 20-50 Castrol. Yep polymers do change with heat. The
base oil is around 7 grade,
with cold polymers will change to 20, when they get hot around
50. I managed to overheat my 12A rotary that I did get
over 280F (pegged gauge) oil temps. Motor did "get me home"
but was trashed from excessive heat. When the oil was drained, it came out
like water! Next morning the engine wouldn't hold water either (aluminum
went beyond critical temps... ). So hopefully someone can check with a
petroleum engine on the polymers and critical temps (my data point is over 20
years ago, not sure if still valid with today's oils)
Other 'seemed like a good idea at the time' was to use Castrol R - hemped
based oil that worked great in our two stoke motorcycles. Three Mazda's in the
rally circuit, three blown engines. Live and learn.
I'm on digest mode, so appreciate everyone trimming their
replies.
Tom
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