2018 Volkswagen Polo 1.0L Petrol · ST18 MMV

A persistent brake pipe corrosion issue defines the mechanical history of this 2018 Volkswagen Polo and warrants close scrutiny before purchase. The most recent test on 10 April 2026 recorded a pass, but with three advisories all flagging corroded brake pipes covered in grease or other material, affecting both the offside rear and the front-to-rear runs on both sides. This was a direct follow-on from the previous day's failed test, where a dangerous defect was recorded for a leaking nearside rear brake pipe on the hydraulic braking system, alongside identical corrosion advisories across all four pipe runs. The pattern suggests the underlying corrosion is systemic across the underbody brake pipework rather than an isolated point failure, and while the immediate leak was rectified to achieve the pass, the advisories indicate that further pipe sections are deteriorating. Earlier tests in April 2025 also produced a failure due to both front track rod end ball joint dust covers being excessively damaged on the nearside and offside, though the subsequent retest on 14 April 2025 passed with no defects recorded, and the April 2024 test was similarly clean. Mileage accumulation over the recorded period sits at 65,777 miles across approximately eight years, giving an annual rate of around 8,200 miles which is broadly typical for a vehicle of this age. There are no extended gaps in the testing history or sudden discontinuities in recorded mileage to suggest the vehicle has been laid up for prolonged periods, which means corrosion findings are more likely to reflect normal in-service exposure to road salts and moisture rather than the accelerated degradation often seen on stored vehicles. However, the brake pipe advisories recorded in both 2026 tests demonstrate that salt and moisture ingress has progressed to the point of hydraulic leakage, which is a significant concern on a car of this age and mileage regardless of usage pattern. A prospective buyer should arrange a physical inspection of the entire underbody brake pipe run, paying particular attention to the rear sections where both the dangerous leak and the grease-covered advisories were logged. The use of grease as a cosmetic cover on corroded pipes should be viewed as a serious red flag, as it masks active surface corrosion and does not restore structural integrity to the steel. On a test drive, listen for any fluid hissing sounds after the engine is switched off, watch for a soft or spongy brake pedal that requires excessive travel, and check for any warning lights related to the hydraulic system. The handbrake should hold the vehicle firmly on an incline, and a visual check beneath the car for any fresh drips or wet residues on the pipes or rear axle is essential. Given the April 2025 failure on both front track rod end ball joint dust covers, the steering and front suspension also deserve close attention even though a clean pass followed. The replacement of these joints on both sides should be verified, and on a test drive the steering should feel precise with no looseness, knocking, or clonking over uneven surfaces, particularly at low speed. Listen for any creaks or rattles from the front end over speed bumps, and check for uneven tyre wear on the front pair which can indicate misaligned or worn suspension components. Beyond the flagged items, a general inspection of the underbody for any further corrosion on structural members, subframe mounting points, and the fuel lines is advisable given the documented brake pipe deterioration, as corrosion rarely develops in isolation on a vehicle that has seen eight winters of road use.