Pokette, S/N 00028 ran very hot from the day I picked it up at Yakima. On my first test flight, oil temp increased past the old 220F red line after thirty minutes in the air (100F OAT). I reduced power and landed thinking there was a problem. None found. Flew the plane to Texas and continued to see 220 -230F on hot days or at altitude. Checked temperature prob for accuracy OK. Checked engine timing OK. About a year ago I added the larger air inlet plenum and 4-in-None exhaust and did not see any detectable difference in the oil temperature. I installed a temperature prob at the oil cooler air inlet and one at the center of the outlet. Air temp in 85F; air temp out 165F proving oil was flowing through the cooler. Oil temp gage stabilized at 215F during this test. I continue to live with 210-230F oil temps except during the winter months and pink cylinders at the exhaust ports. Much of my experience is documented with a string of emails back and forth to CC.
The ultimate solution may be to move back to Alaska where my Cub will find peace and harmony with the environment. The plane is really perfect for cold weather as I get 180F oil temps when there is snow on the ground. Richard