Toyota R150 / R151

Toyota's rear-drive five-speed manual for the body-on-frame vehicles — the Hilux, Fortuner, Innova and T100.

It is a working gearbox in vehicles that are worked, and its faults are the faults of load rather than of design: an enormous number reach very high mileages with nothing but the correct oil.

The recurring complaint is second-gear synchro wear, crunching on a fast cold change and nowhere else — which is what a vehicle driven in traffic and loaded does to a gearbox. A crunch into every gear is the clutch not releasing, which is hydraulic, outside the gearbox, and much cheaper.

The R151F is the four-wheel-drive version, mechanically the same with a transfer case attached, and the letter is the only place the difference is written down.

It takes a gear oil to Toyota's specification, not ATF — the opposite of the Aisin AX-15 — and a heavier oil than specified makes it notchy when cold and hard into second. That symptom has been read as synchro wear on every marque in this catalogue, and the rule is always to read the plate rather than to assume.