Any good ideas on how to harden up dry/brittle wood?

I bought an older playset for my daughter. She really showed interest in one that was at a friend's house so i figured i would suprise her. We couldve bought a new one but I feel like these new ones are way over priced.

This set is about 3 years old, everything is in good shape except the wooden monkey bars. They're not rotten, I just feel like they wouldn't support much weight. Of course, I wiegh just over 200 lbs and my daughter might weigh about 30 right now so its not like theyre made for industrial strength to begin with.

I have it taken apart right now. My plan is to recondition the plastic and paint all the wood to make it new again.

What could I use to help restore the wood? Is there like a deck paint that could do it all in one?

Boiled linseed oil is the first thing im considering but im open to all ideas!

Thanks