Having taken off the outer sills and wheel arch liners it is clear to see the rust on my 2002 Z3 . As due diligence I have scrapped of all the surface rust and poked areas with a screwdriver, cleaned with wire brush, flat angle grinder and wire wheel in drill.
Surprisingly most was top rust and the integrity remains. With the exception in the front wheel arch in top mount rails, which looking is probably common ?
Next was to treat this vehicle with some rust prevention, well having spent years in trade and getting covered in wax oil decided not to opt for the Hammerite due to the smell and dripping and general mess.
Then I remembered DINITROL that I used on a customers car that he supplied and it went on great, less drips and no smell as I remember.
I used REGEL Company and bought the Mazda MX-5 kit aerosols. With the RC900 which is a rust convertor and primer, highly recommend. Sprayed on areas of concern.
Applied a wax oil to the inner sills, removed bungs from wheel arches and filled with wax oil. Sprayed RC900 along inner sills, then covered with black spray undersealer as well as the floor. I must say it went on great. wheel arches done as well.Very pleased.
Result in images...
https://rejel.com/dingkmx5kit1/