During cool and cold weather hydraulic oil drips from the skid plate until until warmed up. The source cannot be seen when the cab is lifted. Changed all oil, ner filter and new case filter, but no help. Thinking there is a seal somewhere that contracts until the oil is warm enough to expand and seal. I cannot store machine inside. I was thinking about a blanket or immersion heater for the hydraulic tank, but concerned about controlling temperature. Thoughts?