This MINI Cooper S was towed in to us. The engine was losing oil and the gearbox was jerky. Here is how we diagnosed and repaired both, together.
Job completed: July 2026
| Car | MINI Cooper S (petrol) |
|---|---|
| Symptom | Engine losing oil, and a jerky gearbox |
| Fault found | No oil leak on the engine; worn valves and heavy carbon on the piston rings were making it use oil; the automatic gearbox was leaking oil and slipping from the low oil level |
| Repair done | Full engine overhaul with new valves and piston rings; full gearbox overhaul with the torque converter replaced; road tested before handover |
| Parts | OEM-grade replacement parts |
| Time taken | Both jobs done in the same visit |
| Cost | Quoted before any work started; extra parts priced item by item for the owner to approve |
| Warranty | 3 years / 60,000km on the engine overhaul; 2 years / 40,000km on the gearbox overhaul |
The car was towed in to us. The engine was losing oil. When we asked how the gearbox felt on the road, the owner told us it was jerky.
The owner had already taken it to another workshop before us. We checked the car ourselves before quoting anything.
This MINI Cooper S pairs its petrol engine with an automatic gearbox.
Inside any engine, the valves and piston rings help keep oil out of the combustion chambers. When the valves wear and the rings clog with carbon, oil slips past them and burns off. The oil level drops even though nothing is leaking.
An automatic gearbox runs on its own oil. It needs the right oil level to grip and change gears smoothly. A leak lets the level fall, and a gearbox run low on oil can slip and jerk.
We checked the engine for oil leaks first. There were none, so the oil was being used up inside the engine. That meant an engine overhaul.
Our diagnostic check also showed a gearbox fault, and the gearbox was leaking oil. We advised overhauling the gearbox and replacing the torque converter together, to solve the gearbox problem.
Then we opened both up. The gearbox had been slipping because of the oil leak and the low oil level. In the engine, the valves were worn and the piston rings had heavy carbon build-up. That was the main cause of the oil use. Two separate problems, each with its own fix.
In the engine, worn valves and carbon on the piston rings let oil get into the combustion chambers, where it burns. That is why the oil level kept dropping with no leak to see.
The gearbox trouble was a separate issue with its own cause. The gearbox was leaking oil. An automatic gearbox needs the right oil level to hold its gears, so with the level low it slipped and felt jerky.
Both faults were repaired together. Doing both at the same time was the practical choice: the car was already in, and the owner got both warranties starting together.
We did a full engine overhaul and a full gearbox overhaul together.
On the engine:
On the gearbox:
After both jobs, our team road tested the car. The test picked up a humming front wheel bearing and worn rear shock absorbers. With the owner's OK, we replaced the front wheel bearings and the rear shock absorbers before handover.
The engine overhaul carries a 3 year / 60,000km warranty. The gearbox overhaul carries a 2 year / 40,000km warranty.
From our team's record of this job. Number plates are pixelated.
The cost depends on what we find inside the engine and the gearbox, so we check first and quote before any work starts.
On this MINI we quoted the engine overhaul and the gearbox overhaul up front. The engine overhaul price covers the engine itself, not the parts around it. Once the engine was open, we listed the other parts worth replacing at the same time, each with its own price. The owner went through the list with us and decided before we fitted anything. That way you know exactly what you are paying for and why.
Check your engine oil level regularly. If you keep having to top up and there is no leak, the engine may be using oil inside. Have it checked early, before the oil runs low. If the oil pressure warning light comes on, stop the car and do not drive it further until the cause is found.
For the gearbox, watch for oil spots under the car, any slip on acceleration, or a jerk when pulling away. A gearbox oil leak can leave the gearbox low on oil, and that is what made this one slip. Fixing a leak early costs far less than a gearbox overhaul.
This MINI Cooper S (Engine overhaul and gearbox overhaul) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For MINI, we use dealer-level ISTA diagnostics. We hold a 4.9★ rating from 1,836+ Google reviews.
WhatsApp us your car model, year and symptoms. We will tell you what is likely wrong and the cost before any work begins. The engine overhaul carries a 3 year / 60,000km warranty. The gearbox overhaul carries a 2 year / 40,000km warranty.
It depends on what we find inside, so we check first and quote before any work starts. On this MINI we quoted the engine overhaul up front, priced each extra part once the engine was open, and the owner decided before we fitted anything. The engine overhaul carries a 3 year / 60,000km warranty.
It depends on the condition of the block and crankshaft. If the block is good and the crankshaft can be resurfaced, an overhaul with new pistons, bearings and seals can restore the engine properly. We check the block and crank first, then advise you on which route makes sense for your specific car.
Yes. Both warranties start from the same date, and the car is off the road once instead of twice. On this MINI Cooper S we did both together, and the owner drove away with a 3 year / 60,000km engine warranty and a 2 year / 40,000km gearbox warranty.
We checked for leaks first and found none, so the oil was being used inside the engine. When we opened it up, the valves were worn and the piston rings had heavy carbon build-up. That lets oil into the combustion chambers, where it burns. So we fitted new valves and piston rings as part of the overhaul.
Yes. A full engine overhaul at our workshop carries a 3 year / 60,000km warranty, whichever comes first. The gearbox overhaul carries a separate 2 year / 40,000km warranty. We confirm the exact terms before work starts.
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