Two questions about silicone and caulk

If you want a long-lasting seal, go to the parts department at your FBO at the local airport and ask for PRC aircraft sealant. It is a 2-part epoxy sealant used in aircraft fuel tanks and pressurized fuselage joints. It is forever.
The reason RV manufacturers do not use it is price. A google search shows a 6 oz. tube is about $40, and a pint can is $80 to $85!
It also requires methyl-ethyl-ketone (MEK) for surface prep and cleanup. That is nasty stuff!

I use high grade silicone on fiberglass all the time.

Been using it on my fifth wheels for years and never had to replace any.

However i do not let it touch the EDPM.

Stay away from silly-cone.

Peel off the loose caulk before applying the new caulk.

handye9 wrote:
DO NOT use silicone on the exterior of your RV. It will not stand up to the weather and, it will leave a residue that prevents other caulking from sticking.

Use Dicor self leveling caulk on the roof (flat surfaces) and use Proflex on the vertical surfaces.

Do a search (here in the forum) for silicone. There are over fifty pages of results.

X2

Actually Dicor sells two versions. Self leveling for roofs and horizontal surfaces. The other formula is for verticle surfaces.

DO NOT use silicone on the exterior of your RV. It will not stand up to the weather and, it will leave a residue that prevents other caulking from sticking.

Use Dicor self leveling caulk on the roof (flat surfaces) and use Proflex on the vertical surfaces.

Do a search (here in the forum) for silicone. There are over fifty pages of results.