Isuzu RZ4E-TC / RZ4F-TC

Isuzu's 1.9 diesel — in the current D-Max and MU-X.

It replaced a 2.5 with a smaller, lighter engine making similar output, which is the design and also the source of every argument about it: a 1.9 in a one-tonne pickup works harder than the 2.5 it replaced, and owners who tow notice.

Its faults are the modern-diesel set and the usage pattern decides them. The DPF on a vehicle used for short journeys is the commonest complaint, and Isuzu's regeneration is sensitive to being interrupted — an oil level rising on the dipstick is fuel dilution from cut-short regenerations, and it is the warning that matters most because diluted oil is what damages the bearings.

The EGR cooler and the intake carbon follow the same pattern and for the same reason.

The RZ4F-TC is the higher-output version in the later vehicles; mechanically the same engine, and the letter is the only place the difference is recorded.