Disco 1 Under-door Trim

The plastic under-door trim strips sure do create a rust trap.
I had a small hole in the horizontal part of the outer sill on the LH side, so I took off the trim to weld in a patch. The condition of the vertical web of the outer sill was badly corroded where the trim strip is fitted. I replaced the entire sill, then took the RH trim off and found similar corrosion requiring new sils.
After fitting the new ones I have decided to not fit the trim. Holes in the vertical webs provide good access for pumping Waxoyl mixed with engine oil into the sills.

Why mix Waxoyl with engine oil?

I have been doing this for very many years on a variety of classic cars and find it works well. Before I spray it into enclosed sections I get it quite warm and it really does flow well.
One place where I have found this to work well is inside the sills of my classic Minis.