Renault H5Ft (1.2 TCe)

Renault's 1.2-litre turbocharged petrol four — the Energy TCe of the Clio, Captur, Mégane, Scénic and Kadjar, and the engine with the worst reliability reputation in Renault's modern range.

The failure is oil consumption progressing to engine destruction, traced to piston and ring problems on a defined production range and aggravated by a turbocharger arrangement that fed oil into the combustion chamber. It was widespread enough to prompt extended warranty coverage in several markets, and the sequence is consistent: consumption that owners do not notice, oil level falling below the pickup, and bearing or piston failure.

So on any 1.2 TCe the first question is oil consumption, and it is a primary question rather than a secondary one — checking and recording the level between services is genuinely the diagnostic procedure. Its 1.3 successor is a different and much better engine, and this reputation must not be transferred to it.