MVC, it sounds as if you may be using the wrong bar oil, or the oil pump isn't working properly. Engine oil will not work to lubricate the bar - you need bar oil, which has an additive that makes the oil very sticky. I've bought it a couple of times at my local flea market - $16 for 4 litres. Great stuff - I use it as way oil on the lathe and milling machine, and anywhere I need oil to stay in place for a long time.
Chainsaw oil pumps are often poorly engineered. Also, if they have ever had dirty oil put in the bar oil reservoir, they are destroyed immediately. If they don't prime properly and pump reliably the bar wears out very quickly. The traditional way to test that the oil pump is working is to hold the saw with the bar end on, a foot away from a fairly light-coloured vertical surface, and rev up the saw. Expect to see a vertical line of oil appear on the vertical surface immediately. If not, shut down the saw and start dismantling the pump - again.
