I have just bought and rebuilt the top end on a 036 pro and now it will pour oil out right after I clean it but won't oil after I make the first cut through 15 inch hickory, I take the bar off and clean it and the saw and it will oil but as soon as I start cutting it quits again, the saw dust is baking on the chain, I've tried three different bar oils and none make a difference, also it's a brand new Stihl 20 inch bar and chain