Lubricants Knowledge Centre

Engine oil reduces friction and wear between moving components. It also helps cool the engine, control deposits, prevent corrosion, support sealing, and carry contaminants to the oil filter.

The grade describes the oil’s viscosity characteristics. The number before “W” indicates its low-temperature performance, while the second number represents its viscosity range at normal high operating temperatures.

The viscosity grade does not, by itself, indicate the quality of the oil.

No. Thicker oil is not automatically more protective. Modern engines are designed around specific bearing clearances, oil-pump capacity, cooling systems, and valve-control technologies.

Use a viscosity grade approved by the vehicle manufacturer while considering ambient temperature and operating severity.

Viscosity describes an oil’s resistance to flow at specified temperatures. Oil quality and performance depend on the complete formulation, including base oils, additive technology, testing, specifications, and manufacturing control.

Two oils carrying the same viscosity grade can provide very different levels of performance.

Mineral oils are primarily produced from conventionally refined petroleum base stocks. Semi-synthetic oils combine mineral and synthetic base stocks, while fully synthetic oils use higher-performance base stocks and carefully selected additives.

Synthetic oils generally provide better low-temperature flow, oxidation resistance, deposit control, and high-temperature stability. However, actual performance depends on the complete formulation—not the base oil alone.

No. Synthetic oil can provide improved resistance to heat and oxidation, but it still becomes contaminated and its additives are gradually consumed.

The correct change interval depends on the engine, lubricant specification, fuel quality, filtration, operating conditions, and manufacturer recommendations.

API classifications define minimum engine-oil performance requirements. “S” categories generally relate to gasoline engines, while “C” categories relate to heavy-duty diesel engines.

The required API category should be selected according to the engine manufacturer’s instructions. It should not be chosen solely because it is newer or more expensive.

SAE primarily defines an oil’s viscosity grade. API and ACEA establish engine-oil performance categories, while vehicle and engine manufacturers may issue their own OEM specifications or approvals.

A suitable oil must have both the correct viscosity and the required performance specification.

Only when the oil carries the required diesel performance classification and is suitable for that particular engine.

Diesel engines may require different soot control, detergency, wear protection, and exhaust-aftertreatment compatibility. Never select an oil based only on its viscosity.

Only if the product also carries the gasoline-engine specification required by the vehicle manufacturer.

Heavy-duty diesel oils may have different additive chemistry and may not be suitable for every gasoline engine or emission-control system.

Many engine oils are generally compatible for emergency top-up. However, routine mixing is not recommended because the resulting mixture may not provide the expected viscosity or performance of either original product.

Whenever possible, top up with the same product or an oil carrying the same approved viscosity and performance specifications.

Dark oil does not necessarily mean that the oil has failed. Detergent and dispersant additives keep soot, oxidation products, and contaminants suspended so they do not accumulate inside the engine.

Oil condition cannot be determined accurately from colour alone.

Not necessarily. Poor-quality or incorrectly specified oil may provide inadequate protection from the moment it enters the engine.

Frequent replacement cannot compensate for weak wear protection, poor deposit control, low oxidation resistance, or failure to meet the required specification.

Severe operating conditions can include:

• Frequent short journeys
• Extended idling
• Stop-and-go traffic
• High ambient temperatures
• Dusty environments
• Towing or heavy loading
• Low-speed, high-load operation
• Poor or inconsistent fuel quality

Vehicles operating under these conditions may require shorter oil-change intervals.

City driving frequently involves cold starts, idling, short journeys, and stop-and-go operation. These conditions can increase fuel dilution, moisture accumulation, sludge formation, and thermal cycling.

Continuous highway driving usually allows the engine and oil to reach stable operating temperatures.

Low-Speed Pre-Ignition, or LSPI, is abnormal combustion that can occur in some turbocharged gasoline direct-injection engines, particularly at low speed and high load.

Severe LSPI events may damage pistons and other engine components. Using an oil carrying the correct modern performance specification is an important part of LSPI protection.

Not always. Finished lubricants contain carefully balanced additive systems. Adding another treatment may disturb this balance, alter viscosity, cause incompatibility, or affect the lubricant’s expected performance.

Supplemental additives should not be used unless specifically approved by the engine or equipment manufacturer.

Unopened lubricants stored correctly can remain usable for a considerable period, but they should not be considered to have an unlimited shelf life.

Storage temperature, moisture, packaging condition, formulation, and product type all influence shelf life. Check the container condition, production information, and supplier recommendations before using older stock.

No. Engine age alone is not enough to justify changing viscosity.

The engine’s condition, oil consumption, operating pressure, manufacturer recommendations, and permitted viscosity range should all be considered. Excessively thick oil may reduce circulation during start-up and interfere with systems designed for a specific viscosity.

The oil level should be checked regularly and before long journeys. Park the vehicle on level ground and follow the manufacturer’s procedure, as checking requirements can differ between vehicles.

A sudden change in oil level or consumption should be investigated.

Automatic transmission fluid must be selected according to the exact specification required by the transmission manufacturer. Colour alone does not identify the fluid’s specification or suitability.

Using the wrong ATF may affect shift quality, friction behaviour, cooling, seal compatibility, and transmission durability.

No. Automatic transmissions, continuously variable transmissions, and dual-clutch transmissions can require very different friction and viscosity characteristics.

Use only the fluid type and specification approved for the particular transmission.

No fluid should be assumed to suit every transmission. A multi-vehicle or universal ATF may cover several applications, but its documented specifications must be checked against the transmission manufacturer’s exact requirement.

ATF contains specialized friction modifiers, oxidation inhibitors, anti-wear agents, seal-compatible components, and other additives. Some of these materials naturally have a distinctive smell.

A new fluid’s normal odor should not be confused with the sharp burnt smell that may indicate overheating or fluid degradation.

Not unless the equipment manufacturer specifically permits it. Gear oil and transmission fluid may have different friction properties, additive systems, viscosities, and material compatibility—even when their viscosity appears similar.

GL-4 and GL-5 describe different gear-oil performance levels and application requirements. GL-5 products generally provide higher extreme-pressure protection for heavily loaded hypoid gears.

However, GL-5 should not automatically replace GL-4 in every manual transmission, particularly where synchronizer compatibility and shift performance are important.

Products with the same viscosity can use different additive technologies and be designed for completely different equipment.

The required performance category, OEM specification, gear design, materials, and operating conditions must also be considered.

ISO VG is a viscosity-classification system commonly used for industrial lubricants. Grades such as ISO VG 46, 68, and 150 identify defined viscosity ranges measured at 40°C.

ISO VG indicates viscosity only; it does not define the product’s complete performance or suitability.

Follow the equipment manufacturer’s recommended viscosity and performance requirements.

Selection may also depend on operating temperature, pump type, system pressure, filtration, water exposure, equipment condition, and environmental conditions.

AW hydraulic oils provide anti-wear protection and are suitable for many conventional hydraulic systems.

HVI hydraulic oils have a higher viscosity index, allowing their viscosity to remain more stable across a wider temperature range. HVI oils are often preferred for mobile or outdoor equipment exposed to substantial temperature changes.

Only when the equipment manufacturer specifically recommends it.

Most hydraulic systems require dedicated hydraulic fluids with particular anti-wear, air-release, filtration, oxidation, and water-separation characteristics.

Water can promote corrosion, reduce lubricant strength, damage additives, block filters, encourage microbial growth, and shorten component life.

Even relatively small amounts of water may create serious problems in sensitive systems.

Foaming may result from:

• Air entering the system
• Low fluid level
• Contamination
• An unsuitable lubricant
• Damaged seals
• Incorrect return-line design
• Poor air-release performance

The root cause should be investigated instead of simply adding an anti-foam treatment.

These oils are formulated for different equipment and operating demands.

• Hydraulic oils are designed for power transmission and pump protection.
• Turbine oils emphasize oxidation stability, rust prevention, air release, and water separation.
• Compressor oils must manage heat, deposits, oxidation, and the requirements of the particular compressor design.

They should not be treated as automatically interchangeable.

Used-oil analysis can measure properties such as viscosity, oxidation, contamination, water content, additive condition, and wear metals.

Trending results over time is usually more valuable than relying on a single isolated test.

Grease is a lubricant made from base oil, a thickener, and additives. The thickener holds the lubricating oil in place where continuous oil circulation is not practical.

Grease selection depends on speed, load, temperature, water exposure, sealing, and component design.

Mixing greases is generally discouraged unless their compatibility has been confirmed.

Different thickener systems or base oils can cause softening, hardening, oil separation, or loss of performance. When changing grease type, the previous product should be removed as completely as practical.

No. Over greasing can increase temperature, damage seals, waste energy, and push grease into unwanted areas.

Apply the correct quantity at the correct interval according to the equipment manufacturer’s recommendations.

Engine coolant combines water with antifreeze components—normally ethylene glycol or propylene glycol—and corrosion inhibitors.

It helps control freezing, boiling, corrosion, deposits, cavitation, and deterioration of cooling-system materials. Plain water does not provide the complete protection required by modern cooling systems.

The main coolant technologies include:

• IAT – Inorganic Additive Technology: Uses traditional inorganic corrosion inhibitors, commonly including silicates or phosphates. It is frequently associated with older vehicles and generally requires a shorter replacement interval.
• OAT – Organic Acid Technology: Uses organic corrosion inhibitors designed to provide long service life and effective protection for many modern cooling systems.
• HOAT – Hybrid Organic Acid Technology: Combines organic corrosion inhibitors with selected inorganic inhibitors, such as silicates or phosphates, to provide rapid and long-lasting protection.
• Si-OAT – Silicated Organic Acid Technology: An OAT-based coolant containing controlled silicate technology. It is specified by various European and other vehicle manufacturers.
• P-OAT – Phosphated Organic Acid Technology: An OAT-based coolant containing phosphate inhibitors. It is commonly specified by several Asian vehicle manufacturers.

Each technology has its own chemical balance and compatibility requirements. Coolants should be selected according to the vehicle manufacturer’s specification rather than technology name or colour alone.

Typical general service-life ranges are:

*These are general guidance ranges—not universal replacement intervals.

Actual service life depends on the vehicle manufacturer, coolant formulation, operating conditions, dilution quality, cooling-system condition, and whether the coolant has been contaminated or mixed with another technology.

Always follow the replacement interval stated in the vehicle owner’s manual or approved coolant product information.

No. “Long life” describes an expected service characteristic, not universal compatibility.

A long-life OAT coolant may still be unsuitable for a vehicle requiring a particular HOAT, Si-OAT, P-OAT, or manufacturer-specific formulation.

The coolant must meet the required vehicle specification and be compatible with the cooling system’s metals, seals, gaskets, and previous coolant.

No. Colour is not a recognized universal technical standard.

Two coolants with the same colour may use different and incompatible technologies, while compatible products may have different colours.

Never select or mix coolant based only on whether it is green, red, blue, yellow, orange, or pink. Check the specification and product documentation.

Mixing is not recommended unless compatibility is clearly confirmed by the coolant supplier and vehicle manufacturer.

Combining different technologies may reduce corrosion protection, shorten service life, cause deposits, or create instability within the cooling system.

If the existing coolant cannot be identified, a proper drain and flushing procedure is safer than adding an unverified product.

Not automatically. The word “universal” generally means that the product is designed to cover a broad range of applications. It does not guarantee suitability for every vehicle, coolant technology, or manufacturer specification.

Before using a universal coolant, confirm that its technical datasheet specifically lists the required vehicle-manufacturer specification or application.

General statements such as “suitable for all vehicles,” colour matching, or broad compatibility claims should not replace specification verification.

Concentrated coolant must normally be diluted with suitable water before use.

Premixed coolant already contains the intended ratio of coolant concentrate and water and should generally be used without further dilution.

Always follow the product instructions because incorrect concentration can reduce heat transfer, freezing protection, boiling protection, and corrosion control.

No. An excessively high concentration does not necessarily improve performance. It can reduce heat-transfer efficiency, increase viscosity, and may even provide less freeze protection beyond the optimum concentration range.

For many products, a mixture of approximately 50% coolant concentrate and 50% suitable water is commonly used. However, the exact ratio must follow the product and vehicle manufacturer’s instructions.

Only when specifically permitted by the coolant manufacturer.

Most concentrated products require dilution because water is essential for effective heat transfer. Premixed or ready-to-use coolant should normally be added without further dilution.

Water quality is important. Tap water containing excessive minerals, hardness, chlorides, or other salts can contribute to scale, corrosion, and deposits.

Deionised, demineralised, distilled, or otherwise approved water is generally preferred, subject to the coolant manufacturer’s instructions.

A small emergency addition of suitable water may help prevent immediate overheating when the correct coolant is unavailable.

However, it reduces antifreeze concentration and corrosion protection. The system should later be inspected for leakage and the correct coolant concentration restored as soon as practical.

Coolant performance may deteriorate early because of:

• Mixing incompatible coolant technologies
• Incorrect dilution
• Poor-quality dilution water
• Oil or combustion-gas contamination
• Rust, scale, or deposits inside the system
• Continuous overheating
• Air entering the cooling system
• Leakage and repeated topping-up with water
• Use beyond the recommended service interval

Check the vehicle owner’s manual for the required coolant specification, technology, concentration, and replacement interval.

Do not rely only on colour or general claims such as “long life” or “universal.”

When seeking technical assistance, provide the vehicle manufacturer, model, year, engine type, current coolant if known, and the specification stated in the manual.

Lubricants should be stored in clean, dry, covered areas away from water, dust, excessive heat, and direct sunlight.

Containers must remain sealed and clearly labelled. Stock should be rotated using a first-in, first-out system.

Indoor storage is preferable. When temporary outdoor storage is unavoidable, drums must be protected from rain, dust, direct sunlight, and extreme temperature changes.

Water can collect on an upright drum and enter through the closures as the drum heats and cools. Proper covering and positioning are therefore essential.

A high-quality lubricant can be damaged by poor handling. Dust, water, fuel, metal particles, and residues from other products can reduce performance and cause equipment wear or system failure.

Clean, dedicated transfer equipment should always be used.

This should be avoided. Residual lubricant from a previous product can contaminate the next one, particularly when transferring hydraulic oils, gear oils, compressor oils, coolants, or specialized fluids.

Dedicated, clearly labelled transfer equipment is the safest practice.

Purchase from an authorized and reliable supplier. Inspect the cap, seal, batch identification, label quality, container condition, and product information.

If the packaging appears altered or suspicious, contact the lubricant supplier before using the product.

No. Country of origin alone does not determine lubricant performance.

Quality depends on formulation, base oils, additive technology, manufacturing control, laboratory testing, traceability, and compliance with the claimed specifications.

The same viscosity grade does not mean the same formulation or performance.

Differences may include base-oil quality, additive technology, volatility, shear stability, oxidation resistance, testing, approvals, production control, packaging, and technical support.

Begin with the viscosity grade and performance specification stated in the vehicle or equipment manual.

Then consider:

• Application
• Operating temperature
• Equipment condition
• Load and duty cycle
• Fuel quality
• Environmental conditions
• Required service interval
• Manufacturer approvals or recommendations

If you are uncertain, contact the VORTEX LUBRICANTS technical team at [email protected]