Di na kailangan niyan, the manufacturer has already spent millions of dollars doing research on preventing corrosion in their cars. Pure marketing gimmickry lang ang aftermarket rustproofing. I still have my non rustproofed 96 model civic with 180,000kms and wala naman kalawang. i think mas nakakasama pa nga yata ng mga ziebart na yan kasi malagkit so ung putik kumakapit, whereas with factory rustproofing its just like painted finish, so dirt washes off easily with soap and water.