best product to clean the underside (Frame) of the car?

[sqenixs]

I want to find something that comes in a spray bottle or aerosol. Hopefully good at removing oil/tar/dirt/mud etc, mainly on painted/coated steel frame. I believe the frame is zinc coated and then painted with something from the factory I'm not sure what. But there is some exposed steel under there and other things that are covered in rust. Should be safe on aluminum, plastic and rubber hopefully.

I've heard all sort of things would work like purple power, simple green, krud kutter, oven cleaner, etc.

[Jacob Harrod AUTOCLEAN]

I'd try the BLACKFIRE Super Degreaser Followed up with the Griot's Garage Undercarriage Spray on the black parts.

[DMiglio]

Any general all purpose cleaner or degreaser should/would work well. Another option I like to do is wheel cleaners, they’ve worked well for me in the past especially in dirty wheel wells and engine bays. Recently used WOWO’s clean wheels and it worked well but tend to use P&S Brake Buster.