In my opinion you cant beat Jotun Butinox.
I swear by it, and the reason I can say with such confidence that it is a great exterior wood preservative is I have used it for years and seen the results years later.
Done right you can expect 5 years plus from it.
Butinox 2 is amazing and what I would recommend it is solid and will last you years, but if you are looking for something translucent Butinox 1 is great.
Here is a little bit about them.
Butinox 1. An exterior, translucent, solvent based woodstain designed for a variety of exterior timber applications including newly primed, previously stained or pressure impregnated wood.
Butinox 2. This opaque solvent-based woodstain delivers exceptional protection for new and existing exterior timber. It is easy to apply and forms a flexible film, which provides excellent weather resistance
Butinox 3 is an opaque waterborne wood stain for outdoor use containing both alkyd and acrylic resins offering the best performance and the longest service of all the stains in the Butinox range
I hope reading this helps keep your wood preserved for many years.
Shaun Drysdale
A+ Decorating Services