Toyota 1GD / 2GD

The KD family's replacement — 2.4 and 2.8 litre common-rail diesels with a variable-nozzle turbocharger, fitted to the current Hilux, Fortuner and Land Cruiser Prado.

The engines carry a full modern emissions stack including a particulate filter, and that is where their characteristic complaint comes from: in markets and duty cycles dominated by low-speed work, the filter cannot complete regeneration, soot accumulates, and the result is a cascade of pressure and temperature codes plus in some cases oil dilution from repeated post-injection. Toyota issued software updates addressing exactly this on early examples, so the calibration level is a legitimate diagnostic question.

Oil dilution is worth understanding rather than dismissing: fuel entering the sump during failed regeneration raises the level and thins the oil, which then damages bearings. A rising oil level on a 1GD is a fault report, not a mistake at the last service.