And just for further information for the past thirty years plus my old farm truck's chassis [ body is rough] has been treated inside and out once a year with a mix of engine oil and diesel, [compressor and spray gun] only the most minor bits of...
Done a couple of these on cars, using the split boot type. Need dextrous fingers to do them. Saves taking the mechanical parts apart. Also need to avoid supergluing yer digits together ----