DSG oil leaks: where they come from and how serious they are
Oil under a DSG car can come from the gearbox seals, the cooler lines or the engine. See how to locate it, what it means for the gearbox and what to do.
Oil on the driveway or a wet gearbox casing does not always mean the gearbox is the source. It does always mean you should find out, because running a DSG low on oil can damage it quickly.
First, is it gearbox oil?
Several fluids can drip under a car:
- Engine oil, dark brown or black, from the front or the middle of the car
- Gearbox oil, which on many DSGs is amber to reddish, often thinner
- Coolant, sweet-smelling, green, pink or blue
- Power steering or hydraulic fluid, on cars that have it
A strip of white card under the car overnight shows the colour and position of the drip. Take a photo for the workshop.
Common sources on a DSG
Reported by workshops and parts specialists:
- Output shaft seals at the side of the gearbox, where the driveshafts enter
- Input shaft or clutch housing seal, which can contaminate the clutch
- Cooler lines and connections on wet-clutch boxes, where oil goes to a heat exchanger
- The pan or filter housing gasket, particularly after a service with a poorly seated seal
- The mechatronic seals
- A breather, if oil escapes through the vent
The engine's rear main seal can leak into the bellhousing and look like a gearbox leak. A workshop can tell by the position and the oil type.
How serious is it?
| Sign | What it may mean |
|---|---|
| A slight weep with no loss | Monitor, note the position |
| A visible drip and falling level | Repair soon |
| Slipping, judder or hesitation with a leak | Low oil or oil on the clutch, stop and have it checked |
| Burning smell | Oil on a hot component, check promptly |
The level of oil in a wet-clutch DSG is set within a controlled temperature range, so a dipstick is not used on most. A scan tool and a procedure are needed. See DSG oil change intervals.
What to do
- Identify the fluid and the position of the leak.
- Have the level checked and the leak traced by a workshop that does DSG work.
- Repair the seal or line, then refill to specification with the correct oil.
- Ask whether the clutches need checking. Oil on a dry clutch is a problem.
Leaks on a used car
A leak is a negotiating point and a warning. Look under the car, check the casing for fresh oil and ask for service records. See buying a used car with DSG.
FAQ
Can I top up a DSG myself?
On most models the fill needs the right oil, the right quantity and a temperature check. Use a workshop.
Is a small leak dangerous?
It can become one if the level falls. Find the cause early.
Will a leak cause judder?
It can, if the level is low or oil reaches the clutch. See judder.
General information only. Check codes, parts and procedures against your own vehicle before you act.