Comprehensive Underbody Rust Prevention and Chassis Care

Place the vehicle on stands or ramps (ensure they are rated for the vehicle weight). Use a high-lumen torch to inspect the entire length of the chassis rails, cross-members, and suspension mounting points. Look for 'blooming' paint or orange staining, which indicates rust forming underneath the factory coating. Take photos of troubled areas to track progression or successful treatment.

Use a wire brush or a needle scaler to remove any loose rust flakes or thick cakes of dried mud/red dust. If you apply a sealant over loose debris, you will trap moisture and accelerate the corrosion process. Focus specifically on the 'pockets' behind the fuel tank and above the spare tyre where debris accumulates.

Perform this work on a concrete pad with good drainage. Cover your driveway with a heavy-duty tarp if you are using oil-based lanolin, as it will stain. Use masking tape and newspaper to cover the brake rotors, calipers, and the exhaust system (especially the catalytic converter and DPF), as coatings on these surfaces can cause smoke or reduced braking performance.

Mix your Salt Neutraliser in a foam cannon or pump sprayer according to the manufacturer's ratio (usually 30ml per 1L of water). Ensure your degreaser is diluted appropriately for the level of grime. In Australian summer heat, ensure the metal is cool to the touch before applying chemicals to prevent flash-drying.

Blast the entire undercarriage with fresh water to remove loose grit. Pay special attention to the inside of the chassis rails through the drainage holes. Continue until the water running off the vehicle is completely clear. This can take up to 20 minutes for a vehicle that has recently been off-road in red dust.

Apply the salt neutralising solution to every square inch of the underbody. Unlike soap, this needs to dwell for 5-10 minutes to chemically react with the salt. Do not let it dry; mist with water if working in high temperatures. This step is critical for vehicles driven in coastal NSW, QLD, or WA.

Apply your alkaline degreaser to the engine's lower block, transmission, and differential housings. Use a stiff-bristled brush to agitate areas with heavy oil buildup. Removing oil is essential because protective coatings will not bond to greasy surfaces, leading to premature failure of the barrier.

Perform a final high-pressure rinse. Once finished, the vehicle must be completely dry before applying oil or wax-based protectors. Use a leaf blower or compressed air to blow water out of crevices, bolt holes, and chassis rail interiors. In 35°C+ heat, 2 hours of air drying is usually sufficient.

If you found bare metal or surface rust, apply a rust converter. The converter will turn the iron oxide into a stable black magnetite layer. Allow this to cure for at least 3 hours (or as per bottle instructions) before proceeding to the barrier coating.

Insert the 360-degree extension wand into the chassis drainage holes as far as it will go. Depress the trigger and slowly withdraw the wand at a rate of roughly 10cm per second. This ensures the internal, unpainted surfaces of the chassis are coated in a thick, self-healing wax barrier.

Starting from the front of the vehicle, spray the lanolin or chassis shield onto all metal surfaces. Hold the nozzle 15-20cm away. You are looking for an even 'wet' look without excessive dripping. Lanolin is excellent because it remains tacky and will 'creep' into welds and tight joins over the next 24 hours.

Apply the coating to leaf springs, coil towers, and control arms. For leaf springs, try to get the product between the leaves. Avoid spraying rubber bushings or boots directly, although high-quality lanolin is generally rubber-safe. This lubrication also helps eliminate 'squeaks' common in dry Australian conditions.

Lightly mist any exposed electrical plugs or sensor housings with a non-conductive lanolin spray. This prevents moisture ingress and 'green death' (copper corrosion) in the wiring loom, which is a common cause of ECU faults in older 4x4s.

Allow the coating to 'set' for at least 4 hours before driving. Remove masking from brakes and exhaust immediately. Use a rag dampened with mineral spirits to wipe away any overspray on the exterior paintwork. The initial smell of lanolin will dissipate within 48 hours.