I asked my dealer if they do any rust proofing or apply a rust inhibitor on their truck frames. Answer i got was...toyota claims they have already done their part so your vehicle doesn't need any further treatment unless specified by toyota themselves. My dealer doesn't do any rust proofing, said you can contact a shop down the road, they undercoat vehicles. When i got home with the new truck this summer i gave it a once over. Seeing only black chassis paint throughout the frame, I took it upon myself to get 1/2 dozen aerosol cans of rp-342, and a good hazmat suit, and have at it. Glad I did, its already been on salty roads here the last 2 months. I've seen a friends 2019 trd and its already showing surface rust areas along the welds. I for one don't plan on relying on toyota hoping to a get a new frame in several years.