The old siding was removed and I carefully pressure washed the original 1908 clear fir siding, which was in excellent condition... but very dirty.
My trusted paint people at Benjamin Moore/Forsyth Paint recommended an oil based primer "Prime Lock", which worked wonders on the old siding.
I am going to have to wait until spring to complete the finish coat of Benjamin Moore - Aura (latex paint). I love this paint. I used it on the Gibson Mansion about six years ago and it is holding up really well. This paint is not cheap but you pay for quality and I do not really want to re-visit painting this mansion for a long time.