The brief
Mr Toto brought his Golf in for a scheduled oil change service, and a service here means putting the car up for a 360-degree safety check, which is where the sharp-eyed technician spotted a leak from the mechatronics, the transmission's hydraulic-and-electronic control unit. Three things in one visit, then: the oil change, the leak, and a battery while it was in. The mechatronics holds its own oil for the hydraulic shifting it does, sealed by gaskets. When those gaskets start to weep, the unit slowly loses that oil, and if it runs low the box won't shift properly and the mechatronics can be damaged. Renewing just the gaskets costs a fraction of a whole new mechatronics, so the prudent move is to reseal it now, before it loses everything. The battery was due replacement too, so that got done with a unit to the manufacturer's spec.
The diagnosis
On the 360-degree safety check the Golf came up with the oil and filter due, a weep from the mechatronics gaskets, caught early before the unit had lost much oil, and the battery due replacement. Nothing was failing yet, this was catching the leak in time and looking after the car. So it was an oil change service plus a mechatronics gasket reseal and a new battery, the wear items refreshed and the leak sorted before it became a gearbox problem.
The work
The engine oil and filter were changed and the other filters and fluids checked and topped. The mechatronics was accessed, the weeping gaskets and seals replaced with genuine VW-spec parts and the unit topped to the right level. The old battery was removed and a new battery to the manufacturer's specification fitted, then registered to the car. The brakes, suspension and tyres were inspected while it was up. A road test confirmed a clean start, smooth running, crisp shifts, the mechatronics dry, the battery holding charge, and no warning lights.
The outcome
Fresh oil and filters, the mechatronics resealed and dry, a fresh battery to spec, brakes and suspension checked, and no warning lights. Mr Toto got the Golf back serviced and the mechatronics leak caught in time. Resealing it now, for a fraction of a whole new unit, is the prudent call, because a mechatronics that runs out of oil is a much bigger bill.
