My evinrude is leaking tw-3 oil out of the exaust cavity after shut down and pulling the oat for theday. 105 deg one of the days.Is this normal? Also I have been draining and replacing my gear oil at frequent intervals(every 8 hrs of operation) and it keeps getting dirty. When I went through the lower the old oil had been in there for 25 years.I am thinking the new oil has a little detergent and the gear box still has some residue causing the dirty gear oil and I am continuing to change frequently. No water in oil,no metal to speak of.Thanks-B

