The Ultimate Guide to All Purpose Cleaners (APC) for Vehicle Maintenance

Ensure all surfaces are cool to the touch. In summer, vehicles must be moved into a shaded garage or under a carport for at least 2 hours. Applying APC to a panel above 35°C will cause the carrier liquid to evaporate instantly, leaving concentrated alkaline salts that etch the paint or plastic. Use an infrared thermometer if available to confirm surface temps are below 30°C.

Thoroughly rinse the vehicle with cool water to remove loose particulates. This is especially vital if the car has been exposed to red dust or coastal salt. Removing these 'loose' contaminants prevents you from grinding them into the surface during the APC agitation phase later.

Prepare three specific ratios based on the task: 1:5 (Heavy Duty) for engine bays and wheel arches; 1:10 (Medium Duty) for exterior trim and bug removal; and 1:20 or 1:30 (Light Duty) for interior plastics and leather. Always pour the water into the bottle first, then add the chemical to prevent excessive foaming inside the bottle.

Identify sensitive materials such as 'piano black' interior trim, unsealed aluminium, or aftermarket leather dyes. Apply your 1:20 dilution to an inconspicuous area (like the underside of a door handle or the bottom of a seat) and wait 2 minutes to check for discolouration or swelling.

Starting with the dirtiest area, spray the 1:5 dilution onto a dry engine bay (avoiding the alternator and air intake). Let it dwell for 4-5 minutes, but do not let it dry. The APC will emulsify grease and oil. Use a stiff detailing brush to agitate heavy deposits around the strut towers and plastic covers.

Apply 1:5 APC to tyre sidewalls and inner wheel arches. You will see the APC turn brown—this is the 'blooming' of antiozonants and road film. Agitate with a dedicated tyre brush until the suds are white, indicating the rubber is medically clean.

Using the 1:10 dilution, spray window seals, badges, and fuel filler caps. Use a small boar's hair brush in circular motions to lift trapped dirt. This is critical for preventing 'black streaks' that run down the paint after rain or washing.

Target the front bumper and wing mirrors where insects have impacted. Spray 1:10 APC and let dwell for 3 minutes. The alkaline nature of the APC breaks down the acidic proteins in the bug guts. Wipe gently with a damp microfibre—do not scrub, as bug shells are abrasive.

Spray 1:10 APC into door jambs and boot shuts. These areas collect grease and dust that standard washing misses. Agitate with a soft brush and rinse with a low-pressure stream of water to avoid flooding the interior.

Switch to 1:20 dilution. Spray the APC onto a microfibre towel first, NOT directly onto the dashboard. This prevents overspray onto the instrument cluster or glass. Wipe down door cards, kick plates, and centre consoles to remove body oils and sunscreen stains.

For modern coated leather, use 1:20 APC. Agitate with a soft horsehair brush to create a light foam. This pulls dirt out of the 'valleys' of the leather grain. Immediately wipe dry with a clean microfibre to prevent the leather from absorbing too much moisture.

For floor mats or fabric seats, spray 1:10 APC directly onto stains. Agitate with a stiff nylon brush. For red dust stains, you may need to repeat this twice. Use a wet/dry vacuum to extract the chemical and dirt for the best results.

This is the most critical step. Thoroughly rinse all exterior areas where APC was used. APC is alkaline; if left in crevices, it can cause corrosion over time. Use plenty of water to ensure the pH of the surface returns to neutral (pH 7).

Wipe the surfaces dry and inspect under a high-CRI detailing light or bright sunlight. Look for 'high spots' or streaks. If a surface feels 'grabby' or looks dull, it may still have chemical residue that requires a second rinse or a wipe with a damp cloth.