Depends on how far you are willing to go to protect the underside of your car.

The cheapest option is SCHWARZ.....Sprays on top of old underseal to give you a fresh layer of sealer.(This prodct is more of a stone chip protection)



The second option is UNDERSEAL.Paints on thick over old underseal.It will give a better protection than SWALTZ but it,s not pretty.

The most expensive option,but in my opinion the best is stuff called 3M BAG SEALER.

You need a compressor to apply it to bare metal so you need to strip off old shit. About 15 bags to do an ESCORT.It,s £7 a bag but the protection is awsome.It,s rubberised sealer and moves with the chassis,so no cracking.Also you can paint over it.

This is the finish on mine.It dries light grey and i then painted it GREY with HAMMERITE to match the body colour.