MOT advisory: engine oil leak, but not excessive
Engines get oily with age. Gaskets and seals harden and let a film of oil through, often around the rocker cover or the sump. The tester saw oil leaking from the engine, but not fast enough to fail the test.
What the tester wrote
| Result | Wording on the certificate | Category |
|---|---|---|
| Advisory | Engine oil leaks: leak, but not excessive | Advisory (pass) |
| Fail | Engine oil leaks: leaking excessively from engine | Major |
What the MOT checks
The MOT fails an oil leak when it drips a pool more than 75mm across within five minutes. It also fails lots of small leaks that add up to the same. Anything less, like damp oily patches or a slow weep, can be noted as an advisory.
Very few cars with this note fail on it at the next test, and many get the same note again. That suggests many of these leaks stay slow.
"You should fail a vehicle if a fluid leak creates a pool on the floor within 5 minutes that’s more than 75mm in diameter or if there are many leaks which collectively leak fluid at the same rate."
MOT inspection manual, section 8.4.1 Fluid leaks. Read it on GOV.UK
How common it is
In 2025 this advisory was recorded on 5.1 in every 100 class 4 MOT tests (1,692,595 of 33,210,774 initial tests). The matching fail was recorded on 0.1 in every 100 (39,560 tests).
The typical car with the advisory was 15 years old with 108,249 miles recorded (medians).
| Age at test (years) | Advisory per 100 tests | Fail per 100 tests |
|---|---|---|
| 0-2 | 0.2 | not shown |
| 3 | 0.3 | not shown |
| 4-5 | 0.7 | not shown |
| 6-7 | 1.5 | under 0.1 |
| 8-10 | 3.0 | 0.1 |
| 11-14 | 7.0 | 0.2 |
| 15-19 | 12.0 | 0.3 |
| 20+ | 15.9 | 0.3 |
'Not shown' means fewer than 1,000 tests in that cell, or a cell hidden so a small one can't be worked out. Age is years since first registration. First MOTs often happen just before a car's third birthday, so many show as age 2.
Does it turn into a fail at the next MOT?
We followed the same cars to their next MOT, 240 to 500 days later (1,125,648 pairs where this advisory was recorded). 1.0% failed on the same item at that next test, and another 47.4% had the same advisory again.
Among cars where this item wasn't noted at all, 0.08% failed on it next time. So a car with this advisory was about 13 times as likely to fail on this item as one without it, though the chance is still small.
These are averages. We can't see what owners did between tests. Some will have fixed the problem, and a fix would stop a fail.
What it usually means for a buyer
This is very much an older car's advisory. It's rare on young cars and gets common as cars age, so a slow weep on an older car isn't unusual. What matters is whether it's getting worse and whether the oil level is kept topped up.
Check the dipstick, look under the car where it's usually parked, and ask whether anyone has looked at the leak. A leak near the exhaust or the clutch is worth a garage opinion before you buy.
Typical fix
The usual fix is a new gasket or seal where it's weeping. Some leaks are cheap and easy to reach, others mean a lot of labour, so get a garage to find the source before you price it. Prices vary a lot by car and garage, so get a quote for the specific car.
Questions to ask the seller
You can read any car's MOT history, including advisories, free on GOV.UK. Our MOT advisory decoder explains the other notes in plain English.
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Sources and limitations
- Data: DVSA MOT anonymised test results and test items, class 4 initial tests, 2024 and 2025 (open data on GOV.UK). Same DVSA data as our MOT dataset.
- 'Fail' includes items fixed at the test centre within an hour (pass after rectification).
- An advisory is a tester's judgement on the day. Testers differ, and some problems are not visible at an MOT.
- The MOT is not a service and does not check the engine, clutch or gearbox in depth.
- Counts under 1,000 are not shown. No make or model figures are published here.
Contains public sector information licensed under the Open Government Licence v3.0. Source: Driver and Vehicle Standards Agency (DVSA), MOT Anonymised Data. Analysis by CarCheckHQ. Not endorsed by DVSA.
Written by the CarCheckHQ team.