The brief
Mr Chong, the one owner of this E60 5 Series, brought it in worn down by an engine that kept drinking oil, topping up between services and never sure where it was going. Oil that disappears without leaking on the ground is being burnt, and burning oil is something to deal with properly because it fouls plugs, clogs the catalyst, and only gets worse. The usual cause when oil vanishes with no external leak is the valve stem seals. Each valve has a small seal at the top of its stem that wipes oil off the stem as it slides, so only a film gets through to lubricate it. Over the years that rubber hardens and cracks, and once it does it lets oil run down the valve stems and into the cylinders, where it's burnt with the fuel, so the level drops and you see blue smoke on start-up or under load. Hardened valve stem seals don't recover, so they get replaced, which is precise internal work, and the timing has to be set correctly afterwards.
The diagnosis
The checks pointed at oil burning rather than a leak, no puddle, oil disappearing, the tell-tale signs of valve stem seals letting oil past. With the engine opened up, the seals were hardened and worn, which is exactly the consumption Mr Chong had been fighting. The rest of the engine was sound, no need to go further than the seals. That's a valve stem seal replacement, careful, tooled-up internal work, with the timing reset afterwards, rather than living with the top-ups.
The work
The engine was opened up to the valve gear, the valve stem seals carefully extracted with the correct special tools, the kind of job that needs precision and focus like surgery, and new genuine BMW-spec valve stem seals fitted on every valve. Everything was reassembled, the gaskets and seals renewed where disturbed, and the timing set correctly to spec with the proper tools at the final stages. The engine was run, the oil level checked, and the consumption confirmed stopped. A road test confirmed a clean start with no smoke, smooth running, the oil level holding, and no warning lights.
The outcome
No more oil disappearing, the level holding between services, no blue smoke on start-up or under load, smooth running, and no warning lights. As Mr Chong put it afterwards: "Revol Carz Garage is by far the best car garage that I have encounter for car repair. They have solved my engine oil disappearing issue with the most reasonable rates." The E60 went home with the consumption fixed at the source. Hardened valve stem seals only get worse and take the plugs and the catalyst with them, so replacing them properly put an end to the top-ups for good.
