Rust on the lower engine part

ZoomZ

As an Aircraft technician who has dealt with corrosion, the only way to get rid of all that is either replacing with new, or removing all components and using media blast to get into the pores.

You can then effectively assess depth of damage.

If all is ok, then clean, prime, paint and add a protective wax coating like above CRC etc.

That is the best way to clean and protect. If the tubing carries any type of fluid, those images do not look like they are salvageable even after clean up.