Engine Lubrication & Oil Service

Frequently Asked Questions About Engine Lubrication and Oil Service

Engine oil performs several functions in an internal combustion engine. In addition to lubrication, it affects heat dissipation, wear protection, and the operation of oil-lubricated components, among other things. Oil level, oil quality, and—in particular—the actual engine oil pressure must therefore always be evaluated in relation to the engine, temperature, and operating conditions. Here, we answer frequently asked questions about oil pressure testing and professional engine oil service.

• Why is engine oil pressure important?

  Engine oil pressure ensures that engine oil is pumped through the lubrication system to the designated lubrication points.

  Depending on the engine, the following components, for example, are supplied with oil:

  • crankshaft bearings
  • connecting rod bearings
  • camshaft bearings
  • valve train
  • turbocharger
  • hydraulic tensioners
  • other oil-lubricated components.

  An abnormal oil pressure reading should therefore not be ignored.

• When should engine oil pressure be measured?

  A mechanical oil pressure measurement can be useful, for example, in the following situations:

  • Oil pressure warning light
  • Unreliable oil pressure reading
  • Unusual engine noises
  • Suspected lubrication problems
  • Suspected faulty oil pressure sensor
  • Repairs to the lubrication system
  • Work on the oil pump or engine
  • Inspection following an engine repair.

  The OP 85 enables a direct mechanical measurement for this purpose, independent of the vehicle’s own sensor.

• How is engine oil pressure measured?

  For the OP 85, the measurement is taken at the connection point of the oil pressure sensor or oil pressure switch.
  
  The vehicle’s original sensor is removed for testing, and the test device is connected using an adapter that matches the thread.
  
  The actual pressure can then be measured under the operating conditions specified by the vehicle manufacturer.

• What is the measurement range of the OP 85 oil pressure tester?

  OP 85 has a measurement range of:

  0 to 10 bar.

  The device uses an easy-to-read NG 80 precision pressure gauge and a 1-meter-long flexible test hose with a DN5 quick-connect coupling

• Which adapters are included with the OP 85?

  The current OP 85 comes with ten DN5 plug-in adapters for various threads, as well as a 90° angle adapter.

  Included are, among others:

  • M10x1
  • M12x1.5
  • M14x1.5
  • M16x1.5
  • M18x1.5
  • 1/8x27 NPT
  • 1/4x18 NPT
  • 1/8x28 BSP
  • 3/8x24 UNF
  • 1/2x20 UNF.

  Additional adapters are available through the Leitenberger adapter lineup.

• Why are different oil pressure adapters needed?

  Oil pressure switches and oil pressure sensors vary depending on the vehicle and engine in terms of:

  • threads
  • sealing surfaces
  • installation orientations.

  A tight and mechanically correct connection is essential for reliable pressure measurement.

  Therefore, the adapter must be compatible with the specific engine.

• Is a universal oil pressure adapter sufficient?

  Not for all vehicles.
  
  A comprehensive adapter set covers many applications, but different engines use different threads and connection geometries.
  
  Therefore, the adapter should always be selected based on the specific vehicle or engine.

• Why is an angle adapter useful with an oil pressure tester?

  Oil pressure transducers are often located in tight or hard-to-reach areas.
  
  The ET 285 90° angle adapter can help establish the test connection despite limited installation space. The OP 85 includes this angle adapter as standard equipment.

• Is there a standard engine oil pressure for all engines?

  No.

  There is no universal oil pressure setpoint for all internal combustion engines.

  The setpoint depends, among other things, on:

  • Engine type
  • RPM
  • Engine temperature
  • Oil temperature
  • Oil viscosity
  • Operating conditions.

  The measured value must therefore be compared with the manufacturer’s specifications for the specific engine.

• Why does oil pressure change with engine speed?

  In many engines, the oil pump is mechanically driven by the engine.
  
  As the engine speed changes, the flow rate and pressure conditions in the lubrication system also change.
  
  Modern engines may also use controlled oil pumps.
  
  For this reason, oil pressure setpoints are often specified for specific engine speeds and operating conditions.

• Why does oil temperature affect oil pressure?

  Engine oil changes its viscosity as the temperature rises.
  
  Cold oil is usually more viscous than oil at operating temperature.
  
  As a result, pressure conditions in the lubrication system can change significantly.
  
  A measurement that does not take into account the specified oil or engine temperature is therefore of limited value.

• Is high oil pressure normal when the engine is cold?

  Oil pressure may be higher when the engine is cold—and the oil is therefore more viscous—than when the engine is at operating temperature.
  
  Whether a specific value is normal must still be determined based on the manufacturer’s specifications.
  
  It does not make sense to set a blanket maximum value for all engines.

• What can cause low engine oil pressure?

  Possible causes may include, among others:

  • low oil level
  • incorrect or unsuitable engine oil
  • excessively high oil temperature
  • engine wear
  • bearing problems
  • oil pump
  • pressure relief valve
  • oil filter
  • intake strainer or intake area
  • internal leaks in the oil circuit.

  The actual cause must be systematically diagnosed.

• Does low oil pressure automatically mean the oil pump is defective?

  No.
  
  A defective or worn-out oil pump is only one possible cause.
  
  Bearing play, oil viscosity, oil temperature, oil level, the filter, the intake system, or the pressure regulation system can also affect the measured pressure.
  
  Therefore, the pump should not be replaced solely because of an oil pressure warning.

• What can cause abnormally high oil pressure?

  In addition to operating conditions such as cold or high-viscosity oil, problems related to the following may also play a role, depending on the engine:

  • Pressure regulation
  • Oil passages
  • Filters
  • Oil specification used

  Here, too, it is crucial to compare the measured value with the manufacturer’s specifications and the respective operating conditions.

• Can a faulty oil pressure sensor trigger a warning message?

  Yes.
  
  A faulty sensor, switch, connection, or electrical signal processing can cause a false warning message.
  
  A mechanical measurement using the OP 85 records the actual pressure independently of the vehicle's own sensor and can therefore help distinguish between a real pressure problem and a problem with the electrical sensing system.

• Can a diagnostic tool check the actual oil pressure?

  On compatible vehicles, a diagnostic tool can display the sensor value recorded by the control module.

  However, this value is still based on:

  • Sensor
  • Wiring
  • Signal processing.

  A mechanical oil pressure measurement checks the physical parameter independently of these factors.

  The two methods can therefore complement each other effectively.

• Should oil pressure be measured only when the engine is idling?

  No, provided that the manufacturer's specifications call for additional test points.

  Oil pressure readings are often specified, for example:

  • at idle
  • at a specified engine speed
  • at a specified operating temperature

  The test should be performed according to the procedure specified for the specific engine.

• Can engine oil be extracted instead of being drained through the oil drain plug?

  For vehicles suitable for this purpose, yes.

  Whether a vacuum oil change is permissible and sufficient depends on:

  • The design of the oil pan
  • Access to the oil
  • The dipstick tube or vacuum port
  • Manufacturer specifications

  Vacuum extraction units and collection containers are available for such applications.

• What equipment does Leitenberger offer for draining engine oil?

  VB 01 and VB 01.1 can be used for appropriate engine oil changes.
  
  The vacuum box stores a vacuum generated by workshop compressed air and can then be used as a portable unit for extraction.
  
  Special engine oil adapters are also available for certain vehicles.

• What is the difference between VB 01 and VB 01.1?

  Both devices operate on the same basic vacuum principle.

  The VB 01.1 also features a fill-level indicator.

  For more details, see Vacuum Extraction Devices and Collection Containers.

• What engine oil adapters are available for the vacuum box?

  Currently available options include:

  • VBA 011 for Mercedes-Benz
  • VBA 012 for VW
  • VBA 013 for BMW.

  The adapters are designed for compatible vehicles in which the oil dipstick tube extends all the way to the bottom of the oil pan.

• Why do you need special engine oil drain adapters?

  In vehicles designed for this purpose, the oil dipstick tube can be used as a designated access point to the oil pan.
  
  A suitable adapter connects to the vacuum box and facilitates a controlled suction process.

• Can all the engine oil be drained from every vehicle?

  No.
  
  The geometry of the oil pan and the drain port varies from engine to engine.
  
  Therefore, you must check the vehicle or manufacturer’s specifications to determine whether an oil change via the drain port is recommended.

• Which is better: sucking out the engine oil or draining it?

  There is no one-size-fits-all answer to this.

  The key factor is the service procedure specified for the specific vehicle.

  Vacuuming can offer advantages for suitable vehicles because it allows the work to be done without opening the drain plug.

  Draining may be required or more appropriate for other engine designs.

  The manufacturer’s specifications take precedence.

• Why is it important to pour engine oil carefully?

  When filling the engine with oil, take care to prevent the oil from:

  • spilling over the engine
  • coming into contact with hot components
  • soiling the engine compartment
  • becoming contaminated with dirt.

  A suitable engine oil funnel can be connected directly and securely to the fill port.

• What is the capacity of the Leitenberger motor oil funnel?

  The EFT-01 funnel has a capacity of approximately:

  1 liter.

  The filling system uses interchangeable adapters for different vehicle manufacturers.

• What is an EFT set?

  The EFT set is a more comprehensive engine oil funnel set.

  It includes:

  • 1-liter funnel
  • five funnel adapters
  • angle extension.

  The current basic set covers applications for Audi, BMW, Honda, Lexus, Mercedes-Benz, Nissan, Porsche, Seat, Škoda, Subaru, Toyota, and VW, among others, and can be expanded with additional EFTA adapters.

• Why are there different types of EFTA adapters?

  Engine oil fill ports vary by manufacturer and engine in terms of:

  • Bayonet fitting
  • Thread
  • Diameter
  • Sealing surface.

  The interchangeable EFTA adapters allow the same funnel to be securely connected to different vehicles.

• What is EFT_Set_MB?

  EFT_Set_MB is a specially configured version of the engine oil filler funnel for Mercedes-Benz applications, including compatible Renault engine applications.
  
  The system can also be expanded with additional adapters.

• What is the EFTW 01 angle extension used for?

  On some engines, the oil fill port is located low or is difficult to reach directly due to other components.
  
  The angle extension allows the funnel to be positioned more conveniently.
  
  It is included, among other items, in the comprehensive EFT kit.

• What is EFT 02?

  EFT 02 is an engine oil filling funnel with a fixed connection.
  
  Unlike the modular EFT system with interchangeable EFTA adapters, the connection on this model is permanently attached to the funnel.
  
  Which version is more suitable depends on the intended vehicle fleet.

• When is it better to buy a funnel set instead of a single funnel?

  A complete set is particularly useful for multi-brand repair shops.
  
  Thanks to various adapters, a single funnel can be used on vehicles from multiple manufacturers.
  
  For a repair shop with a highly specialized fleet, however, a more targeted set of adapters may be sufficient.

• Why are special oil filter wrenches needed?

  Oil filters and filter housings have different:

  • diameters
  • surfaces
  • grooves
  • knobs
  • profiles.

  Using a wrench that fits as precisely as possible reduces the risk of damaging the filter or plastic cap when loosening or tightening it.

• What is the advantage of the Leitenberger oil filter wrench?

  The current OEL keys are machined from metal and are manufactured to match the respective filter profile.
  
  OEL 01.1, for example, is CNC-machined, features a hex drive (SW 22), and is designed to fit a filter profile with a width of 76.2 mm and twelve grooves or ridges.

• Can an oil filter wrench be used on all vehicles?

  No.

  Oil filters come in a wide variety of shapes and sizes.

  That is why the product line includes various OEL models, for example, with different:

  • diameters
  • wrench sizes
  • number of flanges
  • grooves or protrusions.

  The wrench must fit the specific filter or filter housing. The Engine Oil Service page currently lists several models, ranging from OEL 01.1 to OEL 11.

• Why is a custom-fit oil filter bell better than a universal filter band?

  For filters that are difficult to access or are tightly secured, a form-fitting bell that matches the filter's profile can offer advantages.
  
  It engages with specific surfaces or profiles and, depending on the tool, also allows for controlled tightening in accordance with the manufacturer's specifications.

• Can an oil filter be tightened to any torque setting?

  No.
  
  Installation must be performed in accordance with the filter manufacturer’s or vehicle manufacturer’s specifications.
  
  While a suitable tool allows for proper tightening, the required torque value must be taken from the corresponding technical specifications.

• What is FOP 01?

  FOP 01 is an oil and fuel filter opener.

  It can be used to open sheet-metal filters with a diameter of 40 to 120 mm so that the filter element can then be inspected.

• Why should an old oil filter be opened?

  The filter element can provide clues about the condition of the system.

  After opening it, for example, you can check for:

  • metal abrasion
  • chips
  • unusual contaminants
  • other residues

  This is not a substitute for a complete engine analysis, but it can provide additional clues for certain diagnostic tasks.

• Does metal debris in the oil filter automatically mean engine damage?

  No.

  The type, quantity, and origin of any material found must be evaluated by a technical expert.

  If there is noticeable wear, further tests may be warranted depending on the failure pattern, such as:

  • Engine oil pressure measurement
  • Oil or material analysis
  • Compression pressure test
  • Engine pressure loss test
  • Crankcase pressure and blow-by measurement
  • Mechanical engine test.
• Can the FOP 01 also open fuel filters?

  Yes.

  The device is specifically designed as an oil and fuel filter opener and is suitable for corresponding sheet-metal filters within the specified diameter range of 40 to 120 mm.

• Can the color of the engine oil alone be used to assess the condition of the engine?

  No.

  The appearance of the oil alone does not provide reliable information about:

  • oil quality
  • additive condition
  • wear
  • remaining service life.

  Depending on the engine and operating conditions, engine oil can darken relatively early.

  A reliable assessment requires additional information or a proper oil analysis, depending on the specific issue.

• Can you tell by looking at the engine oil whether coolant is getting into the engine?

  Significant changes may be noticeable, but they are not always reliably visible.

  If a connection between the cooling system and the combustion chamber or the oil circuit is suspected, targeted diagnostic procedures should be used.

  Depending on the symptoms, these may include, for example, CO₂ leak tests for the cylinder head and cylinder head gasket or other cooling system tests.

• Does engine oil always have to be changed at fixed mileage intervals?

  No.

  The oil change interval depends on:

  • Vehicle manufacturer
  • Engine
  • Oil specification used
  • Maintenance system
  • Operating conditions.

  General mileage or annual guidelines should therefore not be applied to all vehicles.

• Is the correct engine oil specification more important than just the viscosity grade?

  Yes.
  
  The SAE viscosity grade describes only some of the engine oil's properties.
  
  Modern engines may also require specific manufacturer approvals or specifications.
  
  Therefore, when filling the engine, you must follow the instructions specified for that particular vehicle.

• Can too much motor oil be harmful?

  Yes.

  Depending on the engine, an oil level that is too high can cause problems.

  Therefore, when refilling, you should adhere to the specified oil quantity and check the oil level.

  An engine oil funnel makes it easier to fill the engine cleanly, but it does not replace the need to check the oil level and ensure the correct amount is used.

• Can too little engine oil cause low oil pressure?

  An insufficient oil level can affect the lubrication system and, depending on the situation, lead to problems with the oil supply.
  
  If an oil pressure warning is triggered, you should therefore check not only the oil pressure directly but also the oil level to ensure it is correct.

• What role does the oil filter play in engine oil pressure?

  An oil filter is a component of the lubrication system.
  
  Depending on the engine design, the condition of the filter, bypass valves, and other components can affect pressure conditions.
  
  Therefore, if oil pressure readings are unusual, the entire lubrication system—not just the oil pump—should be examined.

• Can an oil filter test replace an oil pressure test?

  No.

  Opening and inspecting a filter provides information about possible contaminants or wear.

  The oil pressure test, on the other hand, directly measures a physical parameter of the operating lubrication system.

  The two procedures address different diagnostic questions.

• What diagnosis should be performed when the oil pressure warning light comes on?

  A systematic approach might include, for example:

  1. Check the oil level and the specified oil grade.
  2. Check for electrical faults or error codes.
  3. Mechanically measure the actual oil pressure.
  4. Compare the measured value with the setpoint at the specified temperature and speed.
  5. If there is a deviation, further investigate the lubrication system.

  OP 85 is designed for direct mechanical oil pressure testing at the oil pressure transducer connection.

• What diagnostic tests are recommended when unusual engine noises are detected?

  That depends heavily on the type and cause of the noise.

  If a connection to lubrication is suspected, the following factors may be relevant, for example:

  • Oil level
  • Oil specification
  • Engine oil pressure
  • Oil filter
  • Mechanical condition of the engine.

  Depending on the fault symptoms, compression pressure testers, engine pressure loss testers, or crankcase pressure and blow-by meters may also be used.

• What equipment is recommended for a professional motor oil service?

  Depending on your shop’s profile, the following items may be useful:

  • OP 85 oil pressure tester
  • compatible oil pressure adapters
  • vacuum extraction units and collection containers
  • vehicle-specific engine oil adapters
  • engine oil filling funnels and EFTA adapters
  • compatible oil filter wrenches
  • oil and fuel filter openers.

  You can find additional fluid-handling equipment under Pumps and Fluid Handling for Automotive Workshops.

  You can find additional mechanical engine diagnostic tools under Test, Diagnostic, and Service Equipment for Internal Combustion Engines.