The brief
Anna's Golf came in for a straightforward oil change, and while it was up on the ramp the mechanic noticed a drive shaft on its way out. Two jobs in one visit: the oil change, and a drive shaft before it let go on the road. The drive shaft sends power from the gearbox to the front wheel, and at each end there's a CV joint, a constant-velocity joint, sealed inside a rubber boot packed with grease. When the boot splits, the grease flings out and dirt and water get in, so the joint runs dry and wears, which is the clicking you hear on full lock. Left long enough the joint fails completely and the wheel loses drive. A worn CV joint with a split boot is replaced, usually as a complete drive shaft, because it's the safe, lasting fix.
The diagnosis
On the ramp the drive shaft showed a split CV boot with grease flung around the inside of the wheel arch, and the joint had play and would click on full lock, which is a joint running dry and wearing out. The other shaft, the gearbox and the rest of the front were sound. The oil and filter were due, that's what it came in for. So it was an oil change plus a drive shaft replacement: the routine job done, and the failing shaft swapped before it stranded her.
The work
The engine oil was drained and refilled with the correct VW-spec oil and a new oil filter. The failing drive shaft was removed and a new genuine VW-spec shaft fitted, the joints and boots fresh and properly greased, every fastener torqued to the manual figures and the hub nut renewed. The other side's boots were checked while it was apart. A road test confirmed no clicking on full lock, smooth drive, and no vibration.
The outcome
No clicking on turns, smooth drive, no vibration, fresh oil and filter, and a front end that's safe again. The Golf went home with the oil done and the drive shaft sorted. A split CV boot only ends one way, with the joint failing and the wheel losing drive, so catching it at the oil change and replacing the shaft kept a small job small.