Conventional lubricating oils are produced from petroleum base oils that have been refined from crude oil. Their molecular composition naturally contains a broad mixture of hydrocarbon structures.

Synthetic base oils are manufactured or chemically engineered to provide more controlled molecular structures and performance characteristics. This allows lubricant formulators to develop oils with strong resistance to oxidation, improved low-temperature flow, reduced volatility and reliable viscosity performance under demanding conditions.

The finished lubricant is more than its base oil, however. Its additive system also plays a major role in determining wear protection, cleanliness, corrosion resistance, viscosity control and specification compatibility.

Yes. There is generally no special procedure required when changing a properly maintained engine from conventional motor oil to an appropriate AMSOIL synthetic motor oil.

The important consideration is selecting a product that provides the viscosity, industry standards and manufacturer specifications required for the vehicle.

Engines with significant existing sludge, contamination or mechanical problems should be assessed separately rather than assuming a lubricant change will correct an underlying maintenance issue.

Yes. Synthetic motor oils can be used safely in new engines when the product is suitable for the vehicle manufacturer's specified application.

Many modern vehicles are factory-filled with synthetic or synthetic-technology lubricants. There is no general requirement that a new road vehicle must first be operated using conventional petroleum oil.

No. A correctly formulated synthetic motor oil does not cause healthy engine seals to begin leaking simply because it is synthetic.

Modern synthetic motor oils are formulated for compatibility with the seal materials used in their intended applications. Existing leaks can become more noticeable after an oil change, but a lubricant cannot repair worn seals, damaged gaskets or other mechanical faults.

AMSOIL motor oils are generally compatible with conventional and synthetic motor oils of the appropriate type. If an engine is low on oil and the correct AMSOIL product is unavailable, adding a compatible motor oil is preferable to operating the engine with an unsafe oil level.

Mixing oils can, however, dilute the performance characteristics of the AMSOIL formulation. AMSOIL does not support its extended drain recommendations where the motor oil has been mixed with other oils.

It should not be assumed that different AMSOIL products are interchangeable or suitable for mixing simply because they are both synthetic.

Lubricants are formulated with specific frictional, viscosity and additive characteristics for their intended application. This is particularly important for automatic transmission fluids, gear oils and specialist fluids, where the wrong mixture can materially change how the equipment operates.

Use the product designed for the required application rather than blending products to create a substitute.

Motor oil contains an additive system designed to complement the base oil and help it perform under the conditions found inside an engine.

Depending on the formulation, additives may provide anti-wear protection, detergency, dispersancy, oxidation resistance, corrosion protection, foam control, viscosity control and friction modification.

This is one reason two oils with the same SAE viscosity can perform differently and satisfy different industry or manufacturer requirements.

AMSOIL treats detailed formulation information as proprietary and does not base product recommendations solely on whether a lubricant uses a particular category of synthetic base stock.

Different base oils and additive technologies offer different characteristics. AMSOIL selects the combination required to achieve the intended performance of each finished lubricant.

For the customer, the important considerations are the finished product's performance, specifications and suitability for the application rather than a single base-oil label.

Start with the vehicle manufacturer's requirements for viscosity and lubricant specifications, then select an AMSOIL product formulated for those requirements.

AMSOIL Australia provides an online vehicle lookup covering a large range of Australian vehicles. Product pages also list applicable industry standards and manufacturer specifications where available.

Viscosity is only one part of an engine oil's specification.

Oils with the same SAE viscosity grade can use different additive systems and be designed to meet different API, ILSAC, ACEA or vehicle-manufacturer requirements. Offering multiple formulations in the same viscosity allows AMSOIL to cover a much broader range of engines and performance requirements.

For example, two oils may both be SAE 5W-30 while only one carries the particular manufacturer specification required for a specific European engine.

The three product families are designed around different levels of performance and service life.

• AMSOIL OE Synthetic Motor Oil is designed for use at vehicle-manufacturer-recommended oil-change intervals.
• AMSOIL Extended-Life Synthetic Motor Oil provides increased service life and is suitable for extended drain intervals where the product recommendations and operating conditions allow.
• AMSOIL Signature Series Synthetic Motor Oil is AMSOIL's flagship passenger-car motor oil range, formulated with a more robust performance package and longer extended-drain capability.

The longest possible oil-change interval should never be assumed solely from the product family. Follow the service-life recommendation for the specific product and application.

The "W" stands for winter. It relates to the oil's low-temperature viscosity performance.

A multigrade oil such as SAE 5W-30 must meet defined low-temperature requirements associated with the 5W grade while also meeting the high-temperature viscosity requirements of an SAE 30 grade.

It does not mean the oil has a "weight" of 5 when cold and 30 when hot. The two numbers relate to different viscosity tests and operating-temperature ranges.

The vehicle or equipment manufacturer's recommendation should normally be the starting point when selecting viscosity.

Some manufacturers permit different viscosity grades depending on ambient temperature, operating conditions or engine configuration, while others specify a particular viscosity very tightly.

Changing viscosity without considering the engine design, oil-pressure system, variable valve timing, emissions equipment and required specifications may produce undesirable results.

Both matter.

The SAE viscosity grade describes important flow and viscosity characteristics, while standards such as API, ILSAC, ACEA and manufacturer specifications define additional performance requirements.

Matching the viscosity while ignoring a required specification can result in using an oil that is not suitable for the engine. Likewise, an oil carrying an appropriate performance specification may still be inappropriate if its viscosity is outside the manufacturer's recommendation.

Some AMSOIL motor oils are specifically formulated and recommended for extended drain intervals, while others are designed around the vehicle manufacturer's normal service interval.

Extended service life depends on the individual product, engine, operating conditions and maintenance practices. Always follow the service interval published for the specific AMSOIL product and application.

Extended-drain motor oils require the lubricant to maintain protection as both the oil and its additive system are exposed to heat, oxidation, contamination, acids and mechanical stress.

AMSOIL's extended-drain products are formulated to resist oxidation, maintain viscosity, control deposits and retain the additive performance required for a longer service interval.

Extended service intervals are product-specific and should not be assumed for every AMSOIL lubricant.

Lubricant degradation is not determined by distance alone.

Oil is affected by heat, oxidation, moisture, combustion by-products and additive depletion even when relatively few kilometres are accumulated. Engines that spend long periods idling can also accumulate substantial operating time without covering much distance.

For this reason, service recommendations may specify kilometres, operating hours and elapsed time, with the first limit reached determining the oil-change point.

The exact definition varies by manufacturer, so the vehicle owner's manual should be consulted first.

Conditions commonly considered severe can include frequent short trips, prolonged idling, commercial or fleet use, towing, heavy hauling, dusty environments and other operating conditions that place additional stress on the engine and lubricant.

A vehicle does not have to be driven aggressively to qualify for severe service. Repeated short-distance driving or extensive idling can be demanding operating conditions for engine oil.

AMSOIL does not support extended drain intervals where its motor oil has been mixed with another oil.

Although compatible oil may be used for topping-up where necessary, mixing formulations can dilute the additive system and reduce the performance and service-life benefits of the original AMSOIL product.

These organisations publish performance categories used to define the minimum requirements of engine oils for particular applications.

API categories are widely used for gasoline and diesel engine oils. ILSAC standards are closely associated with gasoline passenger vehicles and include requirements such as fuel economy and emissions system compatibility. ACEA oil sequences are widely used by European vehicle manufacturers and cover several gasoline, light-duty diesel and heavy-duty applications.

A vehicle manufacturer may require one of these industry standards, its own manufacturer specification, or both.

Many vehicle manufacturers publish their own lubricant performance requirements in addition to general industry standards.

Examples include specifications issued by manufacturers such as BMW, Ford, General Motors, Mercedes-Benz, Porsche, Stellantis and Volkswagen.

These specifications can address factors including wear, deposits, oxidation, fuel economy, emissions-system compatibility, viscosity and extended service. Always match the exact specification where the vehicle manufacturer requires one.

Many newer API gasoline and diesel categories are designed to provide backward compatibility with earlier categories, but backward compatibility should not be assumed across every lubricant standard.

For example, API CK-4 diesel oils are designed as replacements for many previous heavy-duty diesel categories. By contrast, API FA-4 is a specialised low-viscosity diesel category with limited backward compatibility.

Manufacturer-specific standards and specialist gear, transmission and powersports specifications must be assessed individually.

The key requirement is to use a lubricant suitable for the vehicle and to maintain the vehicle in accordance with its applicable warranty and servicing requirements.

Select an AMSOIL product that provides the viscosity and performance specification required for the application, maintain appropriate service records and follow any manufacturer servicing requirements that apply to the vehicle.

AMSOIL synthetic multigrade motor oils are formulated to operate across a broad temperature range when used in the applications for which they are recommended.

Synthetic base oils can provide strong low-temperature flow while resisting excessive thinning and volatility at high operating temperatures. This is particularly beneficial during cold starts and in high-temperature or high-load operation.

A high-quality synthetic motor oil with low volatility can help reduce lubricant consumption associated with oil evaporation and burn-off in a mechanically sound engine.

Motor oil cannot repair worn piston rings, valve guides, seals, turbocharger faults or other mechanical causes of excessive oil consumption. Unusually high consumption should be diagnosed rather than treated as purely a lubricant issue.

Racing oil is formulated around the operating requirements of competition engines, which can differ substantially from the requirements of a modern emissions-equipped road vehicle.

AMSOIL DOMINATOR Racing Oil uses high levels of anti-wear chemistry suited to racing and high-performance applications. It is not formulated to carry the API service classifications required by many modern passenger vehicles and is therefore not the default recommendation for ordinary street use.

Select oil according to the engine's actual application and specification requirements rather than assuming a racing product is automatically "better" for every engine.

Yes, provided the engine is mechanically sound and the chosen lubricant is appropriate for its design and specification requirements.

High kilometres alone do not prevent an engine from using synthetic oil. However, older engines may have wear, sludge accumulation, hardened seals or other mechanical conditions that should be considered separately.

Sometimes, but not simply because the product is labelled as a diesel oil.

Some heavy-duty diesel oils also carry gasoline-engine performance categories, while others do not. Check the specific product's specifications against the requirements of the gasoline engine before using it.

API CK-4 was designed to provide backward compatibility with earlier heavy-duty diesel categories including API CJ-4 and CI-4+ in applications where those categories were specified.

Vehicle and engine manufacturer requirements should still be checked, particularly where an OEM specification is required in addition to the API category.

API FA-4 was developed around lower-viscosity heavy-duty diesel oils intended primarily for certain newer engines where improved fuel efficiency is required.

Older diesel engines may not have been designed for these lower-viscosity lubricants, so FA-4 should only be used where the engine manufacturer specifically permits or requires it.

Both are multigrade oils that meet SAE 40 high-temperature viscosity requirements, but they differ in low-temperature behaviour.

An SAE 5W-40 oil satisfies more demanding low-temperature requirements than a 15W-40 and will generally flow more readily during cold starts. The correct choice still depends on the engine manufacturer's viscosity and specification recommendations.

Modern diesel engines commonly use exhaust-aftertreatment systems such as diesel particulate filters and catalytic devices.

Lubricant chemistry can influence ash accumulation and the service life of these systems. Older diesel oil specifications may not impose the same limits required for later emissions-equipped engines.

Use an oil meeting the specification required by the engine manufacturer rather than choosing a diesel oil solely by viscosity.

A wet clutch operates with its clutch plates immersed in oil. This arrangement is common in motorcycles and some powersports equipment because the lubricant helps cool and protect the clutch assembly.

The oil must provide suitable frictional characteristics so the clutch engages correctly without excessive slip. This is why motorcycle lubricant requirements can differ from those of a passenger-car engine oil.

It depends on the motorcycle's lubrication system and required specifications.

Many motorcycles use one lubricant for the engine, gearbox and wet clutch, placing different demands on the oil than a passenger-car engine. Friction modifiers suitable for an automotive engine oil may also be inappropriate for some wet-clutch applications.

Use a motorcycle lubricant carrying the viscosity and performance requirements specified for the bike.

AMSOIL advises that its appropriate synthetic two-stroke oils can be used during break-in periods.

Follow the equipment manufacturer's break-in instructions and use the correct AMSOIL two-stroke product and mixing or injection requirements for the application.

In some applications, yes. An appropriate multigrade such as 10W-30 can satisfy SAE 30 high-temperature viscosity requirements while providing improved low-temperature starting characteristics.

Small engines often operate under high loads, elevated temperatures and limited cooling, so a lubricant specifically formulated for small-engine service may be preferable to a general passenger-car oil.

Always confirm the equipment manufacturer's viscosity and specification requirements before substitution.

Automatic transmission fluid is both a lubricant and a functional hydraulic fluid. Its viscosity and frictional characteristics influence clutch engagement, shift quality, cooling and hydraulic operation.

Different transmissions can require materially different fluid properties. Using or mixing fluids that do not satisfy the required specification may cause poor shifting, clutch slip, shudder or component damage.

Different fluid specifications should not be mixed unless compatibility is specifically established for the products and transmission involved.

The fact that two fluids are both synthetic does not mean they have the same friction characteristics or additive chemistry.

Where the wrong fluid has been installed, seek application-specific advice rather than attempting to correct the mixture by adding another fluid.

API GL-4 and GL-5 are gear-lubricant performance classifications designed for different levels and types of gear loading.

GL-5 is not simply a newer version of GL-4 and should not automatically be treated as a universal replacement. Manual transmissions and transaxles may require particular frictional and synchroniser characteristics in addition to basic gear protection.

Use the specification required by the equipment manufacturer rather than assuming that a higher GL number is always better.

Many clutch-type limited-slip differentials require specific frictional characteristics to allow the clutch packs to operate smoothly.

Some gear lubricants contain limited-slip friction modifier as part of the formulation, while other applications may require a separate additive.

Check both the differential manufacturer's requirements and the selected AMSOIL product information before adding additional friction modifier.

Some AMSOIL gear lubricants are designed for extended service, but the appropriate interval depends on the product, equipment, contamination level, duty cycle and manufacturer requirements.

Severe heat, water contamination, towing, heavy loading and off-road conditions can materially affect lubricant life. Follow the recommendation for the specific product and application rather than applying an extended interval universally.