The brief
The A8 had been dropping transmission fluid, with puddles under it after parking, and the owner had been topping it up. The shifting had gone jerky, sometimes delayed, sometimes rough, with a faint burning smell when the dripping fluid hit hot exhaust. He brought it in. Fluid puddles plus rough shifting point at the automatic transmission, and usually at the pan gasket and the filter that seal the bottom of the box. The ATF lubricates and cools the gears and clutches and carries the hydraulic pressure that shifts them, so when the gasket weeps and the level drops, the box runs low and shifts badly, and old, heat-degraded fluid makes it worse. Topping it up keeps it going for a while, but a leak that won't stop and tired fluid is a job for the whole ATF set.
The diagnosis
On the lift the leak traced to the transmission pan gasket and the filter seal, both weeping, with the rest of the transmission housing dry. The fluid that came out was dark and tired, well past its best, which fit the rough shifting. So the call was the full ATF set, drop the pan, new filter, new pan gasket, fresh fluid to the correct spec and level, rather than another top-up that just buys a few months.
The work
The transmission pan was dropped, the old fluid drained, and the old filter and gasket removed. The pan and the magnets were cleaned, a new genuine Audi-spec filter and pan gasket fitted, the pan torqued back up, and the box refilled with the correct ATF to the proper level following the fill procedure for this transmission, with the temperature checked so the level was set right. A road test followed to confirm the shifts were smooth and there was nothing dripping.
The outcome
Smooth, prompt shifts, no fluid puddles, no burning smell, and the level holding. The A8 went home with the transmission back to spec. A leaking pan gasket and tired fluid only get worse, and a transmission run low or on degraded fluid wears its clutches, so doing the full ATF set rather than topping it up protected the box and put the shifting right.
