Castrol A747 vs Motul 800

Both lubricants are intended for use in multi-cylinder, water-cooled two-stroke engines seen in road racing vehicles where combustion chamber deposit management is critical.

Castrol A747 2T has outstanding high-speed and high-temperature lubricity. This oil maintains optimal piston and combustion chamber deposit control. Its most remarkable feature is however to prevent throttle slide sticking in wet weather circumstances.

On the other hand, Motul 800 2T has achieved a perfect synergy by picking esters above other high-performance synthetic base stocks and combining them with a novel additive package.

This innovative Ester Core Technology allows the engine to provide maximum power while maintaining dependability.

This oil allows for ideal lubrication, especially when driving in damp weather. Its extremely high lubricant qualities provide minimum friction and wear. It also cleans and lubricates engines and exhaust power valves along with preventing the sticking of piston rings and exhaust power valves.

Assessment Table

FeaturesCastrol A747 2TMotul 800 2T
Engine Type2-Stroke2-Stroke
Product TypeStreet BikeStreet Bike
QualityPartially Synthetic100% Synthetic
Product RangeMotorcycleMotorcycle
ViscositiesNot ApplicableNot Applicable
Packaging1L Can1L Can

Purpose of these oils:

A747 is only for racing uses. It should not be blended with any other oil, mineral, vegetable, or synthetic, and should not be used in auto lube systems.

800’s formula is designed for Grand Prix Road Racing Teams. Suitable for all fuel grades up to 124 octanes as well as for all racing premix two-stroke engines installed on racing motorcycles and working at high rpm and under heavy load.

Mixing Ratios

These are not ordinary motor oils hence should not be independently used in any case.

There are to be mixed with other oils used in racing motorcycles to enhance their performance in the following ratios:

A747 should be mixed at a 1:40 ratio or 50ml per two liters of gasoline.

Whereas the 800 has a mixing ratio for Road Racing Grand Prix from 3% to 4% (from 33:1 to 25:1) and for Moto Cross Grand Prix is a 2% (50:1).

It is recommended to reduce the proportion by 0.5 in typical situations.

Compatability with the Catalytic Converter

The presence of ash-producing combustible materials inside a motor oil makes it unfit to be used along with the catalytic converters.

This is because the ash residue left by the burning of such oil has the tendency to intoxicate the chemically reactive catalytic converters.

This ash interacts with the chemicals at the conversion site of converters and decreases their capacity to filter out the exhaust air.

Thus an oil with a higher quantity of combustible material poses a greater threat to the health of catalytic converters.

Both these oils have a considerable amount of combustible material mostly consisting of phosphorus and zinc compounds.

However, by in-depth oil analysis, it was declared that the overall combustible materials’ quantity is found to be much higher in 800 when compared with its counterpart.

Therefore, the A747 with a nominal tendency to create ash due to its lower percentage of combustible content is an attractive option to consider.

Sludge Prevention and Removal

Sludge is a universal oil-related problem as after it undergoes the oxidation process, the resultant oxidized oil accumulates all the dirt, moisture, coolant, and other contaminants to create a semi-solid material named sludge.

As it will necessarily occur and there is no way around it, the oil manufacturers decided to introduce detergents and dispersants inside the oil. These additives reduce the sludge generation by separating the oxidized oil and other pollutants from each another.

They are also capable of breaking down the already formed sludge which hinders the flow of oil inside the engine and causes performance-related issues.

The unused oil analysis of both 800 and A747 was done to find out the contents of detergents in each oil.

The results show much higher concentrations of strong detergents like Calcium, Magnesium, and Sodium present in the first oil while the latter does have decent detergent quantities but was not able to compete with its rival.

The higher concentration of detergents in 800 makes it highly effective against the problematic sludge since more effective and numerous detergents will greatly fight the sludge.

Friction Reduction

Oils have special anti-wear additives such as Zinc, Barium, Phosphorus, Titanium, etc to form the lubrication layer over the engine parts. The test was conducted on both these oils to determine the concentration of each and every anti-wear compound and the result shows a definitive lead of 800 against its partner A747.

According to the data, 800 is better equipped to handle the friction and prolong the engine’s life by preventing or minimalizing the wear and tear.


The most critical parameter in determining the oil’s performance is its viscosity since a very thin oil reduces its ability to conduct normal operations at optimal efficiency.

This is because the highly non-viscous oil will lose its effectiveness to cushion metal parts hence will result in friction.

Nearly at room temperature (20° C), these oils were tested for their densities, as the initial densities play a crucial role in dictating the kinematic viscosities at higher temperatures.

Results declares a slight edge victory of A747 over its competitor.

Oils in ComparisonDensity @ 20o C (Kg/m3)
Castrol A747 2T0.930
Motul 800 2T0.926

During Higher Temperatures

The somewhat higher density of A747 helps it achieve higher kinematic viscosities at both the test temperatures of forty and hundred degrees Celsius.

This data is the proof of A747’s better ability to perform at higher operating temperatures.

Oils in ComparisonKinematic Viscosity @ 40o C (cSt)Kinematic Viscosity @ 100o C (cSt)
Castrol A747 2T17819.7
Motul 800 2T15218.7

During Lower Temperatures

On the flip side, the A474 loses its lead in cold conditions as its pour point temperature is slightly higher than that of 800. It will cause it to freeze three degrees before the other oil.

The 800’s ability to better resist cold makes it a favorite in the colder climate regions.

Oils in ComparisonPour point Temperature (Degrees Celsius)
Castrol A747 2T-30
Motul 800 2T-33

Viscosity Index

The Viscosity Index is the representation of an oil’s sturdiness against the temperature-led changes in its kinematic viscosity. The higher the value the more resistance that oil carries.

Following Viscosity Indexes are calculated by observing the trends in the decrease of kinematic viscosities of both the oils when the temperature was increased from forty to a hundred degrees Celsius.

Even though the initial and final kinematic viscosities of 800 are lower but it loses a lesser value of kinematic viscosity, therefore, its Viscosity Index is higher than that of the other one.

Oils in ComparisonViscosity Index (VI)
Castrol A747 2T127
Motul 800 2T140

Temperature Endurance

Another important factor in deciding the effectiveness of an oil is its flash point temperature which is used to determine the temperature endurance.

A higher flash point means that oil will vaporize slowly and will come to its flash point (Vapor Ignition point) at a higher temperature.

The flash point temperature of 800 is higher than that of its counterpart, indicating that it will vaporize less, therefore, will be consumed lower, which improves its fuel economy as well.

Oils in ComparisonFlash Point Temperatures (Degrees Celsius)
Castrol A747 2T> 200
Motul 800 2T274

Quick Summary

Characteristics Castrol A747 2TMotul 800 2T
Chemical StrengthMediumHigh
Application RangeMediumMedium
Compatibility with the Catalytic ConvertersMediumLow
Sludge Removal CapabilityMediumHigh
Viscosity IndexMediumMedium – High
Friction EliminationMediumMedium – High
Hot climate PerformanceMedium – HighMedium
Cold climate PerformanceMediumMedium – High
Temperature ResistivityMediumMedium – High
EconomicsMediumMedium – High