Use this when you reinstall the windows. Every year all the screws on the inside of the frames should be hand tightened with a screwdriver. This sealer lasts about 10 years then needs replacing. Many RVs are ruined by people who have no idea how important it is to keep the window screws tight and the sealer tape replaced every 10 years or so. Without doing that, water will leak inside the walls unnoticed and rot the wall/floor connection. Pretty hard to repair that. Smearing silicone around the outside of the frame will only leak again very quickly then nothing, even more silicone, will stick there. The butyl tape is what the windows were engineered for and is the only thing that will stand up to the flexing and twisting going down the road (but still need that annual tightening). After about 10 years, the tape is crushed down to where the metal frame is touching the RV wall and then, unless new tape is installed, it will leak no matter how tight the screws are.
https://www.amazon.com/Kohree-Sealant-30-Foot-Sealing-Patching/dp/B07V366FCM/ref=sr_1_1_sspa?crid=WVQSFSLA3H97&keywords=butyl+tape+rv&qid=1580435551&sprefix=butyl+tape%2Caps%2C225&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzMU1KNUNBUlJUREhYJmVuY3J5cHRlZElkPUEwNjc3MTY5MktEVFpFTjYwU0tSQiZlbmNyeXB0ZWRBZElkPUEwNTg4MDg1UlFUU0lIMVVaUlkwJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
