Aisin AF50-8

Aisin's transverse eight-speed for General Motors — in the Buick LaCrosse and the Cadillac XT5.

GM built its own transverse nine-speed at the same time, so these two models sat beside cars with a 9T50 and nothing on either says which is fitted. A ratio count is the tell, and the parts and procedures do not overlap.

Its recurring complaint is a hesitation or a shunt at low speed, particularly rolling back onto the throttle in traffic — the transmission deciding between two nearby ratios. It responds to adaptation and to software far more often than to parts, and both GM and Aisin issued transmission control updates for it.

Where genuine faults appear it is the valve body and its solenoids, presenting electrically rather than by slipping.

The fluid is Aisin's own specification and not a GM Dexron, which is the mistake a workshop reading the badge rather than the transmission would make — the same trap as the Hyundai gearbox in a Jeep.