Cleaner for Engine and frame Rust Parts

Just bought 03 camry, and found that the battery liquid somehow contaminated the area underneath the battery at some time in the past. This included some of the frame, painted area of the inner fender and transmission housing. I plan to clean the painted surfaces with soap and water since it seems like surface rust, but the transmission housing is hard to do, so I may sand it with sand paper to the best I can. Even though I sand it down, rust is still deep down in small pores. Any recommendation for a rust cleaner and rust protection that I should use after cleaning.

Would appreciate

I used Rustoleum rusty metal primer followed by some Rustoleum paint, when something similar happened to my 86 Camry years ago. I would still sand off as much rust as possible first, as you said you were going to do.

Mike

First neutralize the acid by pouring a mixture of baking soda and water. Keep dousing it until it doesn't fizz anymore. Then rinse with water.

I'll also suggest the use of RustOleum's Rust Converter prior to the primer for any rust that can't be reached.

If you can remove the battery tray to prep and paint it (it's probably just as bad underneath as it is on top) then you'll have better access to the damaged paint underneath. I like the 3M Paint and Rust remover wheel in a power drill for large areas of mostly surface rust with some pitting. A coarse 3M scouring pad for harder to reach areas. Unless there's oil or grease contamination of the area, I wouldn't use soap, just clean water and air dry...compressed air quickens the drying time. Any left over rust gets a shot of converter then primer and color coat. Since it is inside the fender, you don't need a clearcoat Hope this helps!