If masonite siding has deteriorated and the plies have come apart ("ruffles"?) it is probably best to replace it. The plies are held together with sawdust, and wax, which leach out when the siding is aged. For painting, a full prime with an alkyd exterior primer, followed by an acrylic topcoat should be fine.

 

thanks....I cant afford to replace all the siding...looking for a an alternative to make it last another 5 year ...

the ruffling is very small along the edges....was hoping there is way to seal it before painting...

the bad sections, I'm planning to replace...

 

When we were called out to repair that type of siding, we would cut the siding off at the bottom just high enough to install a 1X12 with a drip cap on top of the 1X12. Usually that is where the damage was or that is where the damage starts. When we installed a 1X12 we always sealed the raw edge of the siding or it would not last long.

If the siding is bad higher than a 1X12 will fix, you can still fix it but it won't look as good. Cut the siding where there is good material, install a Z flashing and install new siding below. Chances are you will not be able to match the siding there now but the looks are up to you if you can tolerate it not. JMHO