I am a strong believer / promoter of Cabot Semi-Solid, oil based stain. I used it on my mom's barn. The previous application lasted 18+ years before fading.
This picture was taken a few days before Christmas. The barn was stained 4 years ago. This is in Georgia so the sun beats on it relentlessly.
The siding is T1-11 plywood, which hasn't rotted or deteriorated in any way over the last 42 years. No sealer needed with oil based stain. Applied to a truck bed that sits in a garage, it should last forever.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)