Originally Posted by
Roelof
If the adding of a lot of castor oil and running of almost a liter is true then the piston looks too clean!
That piston looks like it comes from an oilbath lookin at the polished part above the small oil ring.
I have older engines with year's of fuel run threw them and they look just as clean like new condition. It's the castor oil that cleans the engine. No castor oil then you will get discoloration.