Q: undercoating

If your vehicle is already in service, there is probably some rust and corrosion already on the underbody. Undercoating is useless on those segments because the rust will simply continue unabated once coated. There is little, if any added benefit, to adding to factory applied coatings these days in terms of corrosion protection. If you look beneath your vehicle, the areas that are not corroded will probably remain in good condition through the service life of the car. What would be worthwhile doing, if you intend to keep the car for 10-20 more years, is fix the areas that have started to corrode using appropriate rust removal techniques and appropriate coatings. Blend those areas into the intact factory applied undercoating and be done with it. In other words, it’s better to focus your efforts on cleaning up any damage that has already started, and get those segments coated, because just applying a coating wholesale over the whole underbody will do nothing to stop the progression of damage in the already rusted areas. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.