This morning when I am filling the wind shield washer, I noticed rust on the sub frame. Especially below the radiator, at the edge of the sub frame where two metals come together.

My plan for this summer is

1.Use this first to remove the rust.

2. Wash and dry. With a metal brush, clean all the rust.

3. Then spray a rubberised under body coating. To the edges of the subframe.

What do you think?

as optimistic as i am, to doing things right, your plan is a waste of time. you will NEVER rust proof a car. you have no idea how much rust there is on the bottom of our cars. if you are going to spend time chasing it around, you will be doing this every day for 3 years.

furthermore, spraying rubberized coating, is a waste of time, unless you properly treat, remove, and kill the rust fungus. (leaving even a tiny speckle will kill all of your hard work)

Well it can't hurt anything but I agree if you let this surface rust bother you it bring you nothing but grief!!! I have actually used a black rust inhibiting/penetrating paint on sections of the lower frame around the back tires because its highly visible and looks terrible. With minimal prep that rust inhibiting paint has done a great job, but I have to re-do the project every 2 years, but I'm ok with it because it takes 10 minutes tops and makes a big difference. If I was going to do this for the entire car it would be losing battle.

I prefer rust converter which becomes a primer black.

POR15 makes an incredible line of products to deal with rust. I would strongly recommend looking into them if you're serious about it.

http://www.por15.com/