Insolubles in the oil should not be a problem if you are changing the oil regularly. But insolubles could be a problem if you have re-jetted and are running too rich.
Insolubles may be forming because your oil use interval is too long for the condition of the engine. Your oil filter may be inferior. It is possible the oil filter bypass valve has relived if the filter is becoming restricted. The filter system bypass may also open upon unusually cold starts when the oil is too thick to pass through the filter media. Once the bypass relieves, the filter is effectively out of the system.