Oil level rising: causes and the faults that trigger it

1. 1. Diesel from the particulate filter passing into the sump

   Common cause

   Autofácil explains that during regeneration the engine injects extra fuel to heat the filter and that the excess can seep past the cylinder walls into the sump, mix with the oil and raise its level; it adds that changes in the level usually point to a problem with the filter. A thread with a Honest John column and a thread of Volvo D5 owners describe the same thing: the control unit adds fuel to regenerate and some of it ends up in the sump.^[1][2][3]

   Faults with with the particulate filterP2002P2463

2. 2. Regenerations interrupted by short journeys

   Common cause

   Autofácil points out that short, low-rev journeys produce particles without giving enough heat to burn them off and that interrupting the process can leave the filter clogged. In the Fiat thread, a moderator maintains that if regeneration is cut off again and again, unburnt fuel is left in the cylinders and ends up draining into the sump.^[1][2]

   Faults with with the particulate filter

3. 3. Worn rings or cylinders that let more fuel through

   Possible cause

   In a thread of Land Rover owners, a participant maintains that fuel reaches the sump after every injection, whether or not regeneration succeeds, and that it does so mainly with worn rings or scored cylinders; he adds that good ring sealing reduces the amount. It is a forum opinion, not manufacturer data.^[4]

   Faults with with the big-end bearings and pistonsFaults with with oil consumption

4. 4. Injector seals or other fuel leaks

   Uncommon

   In the Volvo thread a user cites faulty injector seals as a possible cause of diesel entering the oil, comparing it with a similar problem on another make; it is not confirmed for that model.^[3]

   Faults with with the injectors

5. 5. Coolant passing into the oil through the head gasket

   Uncommon

   Autopista lists among the symptoms of a damaged head gasket rapid loss of coolant, overheating, oil mixing with coolant, excess smoke and loss of power. None of the open sources links that fault to a specific rise in oil level, so it is included as a cause to rule out, not as the usual one.^[5]

   Faults with with the head gasket

1. Measure the level when cold, with the car on level ground and the dipstick clean, and note the date and mileage to see whether it keeps rising. Honest John, in the Fiat thread, suggests checking it every week.^[2]
2. Smell the dipstick: a smell of diesel points to dilution, which is the picture in the Volvo and Land Rover threads. If there is also coolant loss or a mixing of fluids, Autopista associates it with the head gasket.^[3][5]
3. Check whether the coolant level is dropping at the same time, because Autopista cites coolant loss among the symptoms of the head gasket.^[5]
4. Think about how you use the car: short journeys or interrupted regenerations favour dilution according to Autofácil and the Fiat thread. Don't switch off the engine during a regeneration (idle revs rise and you notice heat and a smell at the exhaust).^[1][2]
5. Ask the garage to read the state of the particulate filter and the dilution counter, and consider a laboratory oil analysis; the Land Rover thread cites one for around £40. After changing the oil, the oil degradation index has to be reset, which is independent of the service reminder (Fiat thread).^[2][4]

Urgency: Garage soon

The sources agree that it should not be ignored. The Fiat thread warns that diluted oil can lubricate the bearings poorly and, in the worst case, seize the engine, and in the Volvo one a participant warns that with too much oil the engine can run away on its own oil. While it is being diagnosed, the sensible course is not to add oil, keep the level below the maximum, avoid switching off in the middle of a regeneration and go to a garage soon. If the coolant also drops, the temperature rises or white smoke appears, stop driving. No source says how many kilometres can be driven with diluted oil.^[2][3][5]

1. • High severityFrequency: Very frequentOM642Oil cooler seal leak (between the cylinder heads)The oil level may rise abnormally if coolant enters the oil circuit through the damaged seal, according to one specialist source.Repair (garage): €1,500–€2,200Appears at around 120,000 km

   Source for the symptom in the OM642^[6]

2. • High severityFrequency: Common1.3 MultijetIncomplete particulate filter regenerations and oil dilutionThe oil level on the dipstick rises instead of falling, a sign that it is mixing with unburnt diesel.

   Source for the symptom in the 1.3 Multijet^[7][8]

3. • High severityFrequency: Common2.0 Ingenium diéselFuel dilution of the oil linked to particulate filter regenerationsThe oil level rises between services because the fuel injected during particulate filter regenerations leaks into the sump instead of burning off completely.

   Source for the symptom in the 2.0 Ingenium diésel^[9]

4. • High severityFrequency: CommonMZR-CDOil dilution from leaking injector seals and DPF regenerationsThe dipstick level rises between oil changes and it may smell of diesel if the dilution is high.

   Source for the symptom in the MZR-CD^[10]

5. • High severityFrequency: CommonSkyactiv-DOil dilution with diesel during DPF regenerationsThe level shown on the dipstick rises above normal between oil changes; on the first CX-5 units the warning light did not alert you even when the dilution was excessive.

   Source for the symptom in the Skyactiv-D^[11]

6. • High severityFrequency: Common1.8/2.2 DI-DClogged particulate filter and oil dilutionThe oil level rises above the maximum on the dipstick or the on-board computer when fuel from regeneration seeps into the sump.

   Source for the symptom in the 1.8/2.2 DI-D^[12]

7. • Medium severityFrequency: CommonBMW B47Particulate filter (DPF) clogging in urban useThe oil level may rise if failed regenerations dilute the oil with fuel, according to a specialist workshop.Repair (garage): €500–€1,800

   Source for the symptom in the BMW B47^[13]

8. • Medium severityFrequency: Common2.0 CDTIClogged particulate filter (DPF) and oil dilution on short journeysThe oil level may rise because of diesel fuel getting in during DPF regenerations that are never completed.

   Source for the symptom in the 2.0 CDTI^[14]

9. • Medium severityFrequency: CommonSubaru bóxerClogged particulate filter on the EE20 dieselAUTO BILD lists a rising engine oil level alongside clogged particulate filters; it also records owners without that problem.

   Source for the symptom in the Subaru bóxer^[15]

10. • Medium severityFrequency: Common2.5 TDI R5Leaks and play in the unit injectorsIf diesel gets into the oil, the level rises.

    Source for the symptom in the 2.5 TDI R5^[16]

11. • Medium severityFrequency: OccasionalSmartstream 1.6 T-GDiPetrol dilution of the oil on short journeysThe oil level on the dipstick rises over time without any oil having been added, and the oil smells of petrol.

    Source for the symptom in the Smartstream 1.6 T-GDi^[17]

12. • Medium severityFrequency: Occasional1.4 16v and 1.6 MPI/FSIOil consumption, especially on the older 1.4 16vYou have to top up the oil between changes more often than you would expect.

    Source for the symptom in the 1.4 16v and 1.6 MPI/FSI^[18]

13. • Medium severityFrequency: Rare1.0 / 1.5 VTEC TurboPetrol dilution of the oil in the 1.5 VTEC Turbo on short journeys in cold weatherThe oil level may rise and smell of petrol; the European sources consulted do not detail symptoms.

    Source for the symptom in the 1.0 / 1.5 VTEC Turbo^[19]

14. • Medium severityFrequency: Rare2.4 / 2.8 D-4D (GD)Diesel dilution of the engine oil from interrupted particulate filter regenerationsThe oil level rises on the dipstick without oil having been added.

    Source for the symptom in the 2.4 / 2.8 D-4D (GD)^[20][21]

Engines

• OM642Mercedes-Benz, Jeep, Chrysler, Dodge and Freightliner1 fault with this symptom
• 1.3 MultijetFiat, Lancia, Alfa Romeo, Opel, Suzuki and Ford1 fault with this symptom
• 2.0 Ingenium diéselLand Rover and Jaguar1 fault with this symptom
• MZR-CDMazda1 fault with this symptom
• Skyactiv-DMazda1 fault with this symptom
• 1.8/2.2 DI-DMitsubishi1 fault with this symptom
• BMW B47BMW and MINI1 fault with this symptom
• 2.0 CDTIOpel and Vauxhall1 fault with this symptom
• Subaru bóxerSubaru1 fault with this symptom
• 2.5 TDI R5Volkswagen1 fault with this symptom
• Smartstream 1.6 T-GDiHyundai and Kia1 fault with this symptom
• 1.4 16v and 1.6 MPI/FSIVolkswagen, Seat, Škoda and Audi1 fault with this symptom
• 1.0 / 1.5 VTEC TurboHonda1 fault with this symptom
• 2.4 / 2.8 D-4D (GD)Toyota1 fault with this symptom

Cars with the affected versions

• Excessive oil consumptionUrgency: Garage soon71 faults cause it in 63 engines
• Increase in fuel consumptionUrgency: Monitor33 faults cause it in 28 engines
• Coolant loss with no visible leakUrgency: Garage soon61 faults cause it in 50 engines