My home was built in 1920 and has wood lap siding as its exterior surface. Although this siding is 88+ years old, it still bleeds a considerable amount of sap in certain areas... This is only part of the dilemma. This old siding just doesn't seem to hold onto the paint. It was painted 3 years ago: one coat oil-based primer then 2 coats of latex. It needs repainting already, and, this time, I hope to get it done correctly and have it last just a little longer.

- Is there a sealer I should use before priming?
- Any way to prevent the sap from bleeding through?
- What primer is best suited to tackle this difficult task? & is it oil-based or latex?
- Which exterior paint is best prepared to bond and hold?

I really know very little about painting, so any suggestions/advice would be greatly appreciated!