The current status of 0W-30 engine oils

The low viscosity 0W-30 engine oils enjoy a growing confidence among car manufacturers. The German manufacturer BMW also relies on the high-performance 0W-30 oils and legitimized their use by introducing the BMW LL-12 FE approval. The associated BMW TwinPowerTurbo Longlife-12 FE 0W-30 engine oil (for diesel engines) is supposed to convince with its fuel-saving and ash-reducing properties. In combination with innovative additive packages, this protects the diesel particulate filter (DPF) and achieves a better cold start.

In addition to the approvals of the automobile manufacturers, the specifications also play an important role. The ACEA C2 specification often appears in connection with the 0W-30 engine oils. 0W-30 oils that are based on this specification are referred to as Mid-SAPs engine oils. Among other things, they have specific values in the range of HTHS viscosity (≥ 2.9 mPa`s), phosphor (0.07 - 0.09%), sulfur (≤ 0.3%) and sulphate ash (≤ 0.8%).

The low viscosity 0W-30 engine oils with an ACEA C2 specification are compatible with exhaust aftertreatment systems and extended oil change intervals. In order to be allowed to label a 0W-30 engine oil with this specification, however, the above-mentioned chemical properties must be observed.

In this context, the question of whether the engine oils can be distinguished from each other at all if they have the same approvals or specifications is increasingly being asked. A perfectly legitimate question, but one that can be clearly answered in the affirmative. Despite the trend-setting approvals and specifications, every engine oil has a unique chemical property. This allows engine oils to be compared directly with each other, for example by an oil analysis.

Inhaltsverzeichnis

1. Which 0W-30 oils are the best ones?

2. The tested 0W-30 engine oils

3. Viskosity at 40 degrees and 100 degrees

4. Viscosity Index

5. High Temperature High Shear (HTHS)

6. Total Base Number (TBN)

7. Sulphate Ash

8. Cold Cranking Simulator (CCS)

9. Mini Rotary Viscometer (MRV)

10. Volatilization according to NOACK

11. Pourpoint

12. Flash Point

Which 0W-30 oils are the best ones?

Due to the comparability mentioned above, the question of which 0W-30 engine oil is best is investigated above all. In general, it is like a farce when oil manufacturers advertise their engine oils as the best oil on the market. In particular, engine oils are characterized by multiple interactions in their chemical properties. Put simply, the improvement of one property can lead to the deterioration of another.

It is therefore more a question of the balance between these properties. Every engine oil and therefore also 0W-30 engine oil has different strengths and weaknesses. If, therefore, a comparison is made on the basis of specific properties, this is much more meaningful.

To enable such comparisons, we have had nine different 0W-30 engine oils tested by an accredited laboratory in Germany. The following points were analysed:

▶ Viscosity at 40 degrees

▶ Viscosity at 100 degrees

▶ Viscosity Index

▶ HTHS

▶ TBN

▶ Pour Point

▶ Sulphate Ash

▶ NOACK

▶ Flash Point

▶ CCS -35 degrees

▶ MRC -40 degrees

The tested 0W-30 engine oils

A total of nine high-quality 0W-30 engine oils were tested, all of which have the ACEA C2 specification and mostly the BMW Longlife-12 FE approval and are thus oriented to the very new BMW approval. Beside the original oil BMW 0W-30 LL-12 also the international brand products around Motul Specific LL-12 FE 0W-30, Shell Helix Ultra 0W-30 ECT C2/C3, Mobil ESP 0W-30, Castrol Edge Professional E 0W-30 as well as the Total Quartz Ineo First 0W-30 were analysed. The German manufacturer products include the Liqui Moly Top Tec 6100 0W-30, Ravenol FES 0W-30 and the Fuchs Titan GT1 LL-12 FE 0W-30.

In the following graphic we have compared these engine oils again.

Test results of the analysis

The test results are shown in the following bar charts. They do not appear in alphabetical order, but in numerically order. In addition to the following results, we have put them together in a PDF. This can be found under the following link: PDF ATO24 0W-30 oil analysis.

Viscosity at 40 degrees and 100 degrees

With decreasing temperatures the viscosity of an oil increases. On the other hand, an increase in temperature leads to a decrease in viscosity and the oil becomes thinner. In order to investigate these viscosity changes at increasing temperatures, the oil gets heated till 40°C and 100°C

Intermediate information: The viscosity grade is not proportional to the temperature. An engine oil at 100 degrees would therefore not be twice as thin as one at 50 degrees. For this reason, the two mentioned temperatures are used to investigate the individual changing viscosity grade under increasing temperature conditions.

The result of this investigation is described as kinematic viscosity. Its result is output in mm²/s. These values indicate the time the engine oil needs at the respective temperature to flow through a test defined distance. The less mm²/s the engine oil needs to flow at these temperatures, the thinner it becomes at high temperatures. It therefore changes its viscosity faster (becomes thinner) and reacts faster to temperature changes. A higher value implies a higher viscosity stability. The engine oil would therefore retain its initial viscosity for a longer period of time as the temperature rises and would lubricate the engine constantly.

➥ In short: The higher the result values (mm²/s), the more constant the viscosity remains at high temperatures and thus allows longer constant lubrication despite increasing temperature changes.

Viscosity Index (VI)

The viscosity index (VI) deals with the viscosity at different temperatures. The VI is a paramter which is measured at temperatures of 40°C and 100°C (the result from the point "viscosity at 40°C and 100°C"). The viscosity index is represented in natural numbers. The higher the viscosity index value of an engine oil, the less the initial viscosity changes at higher temperatures.

However, it must be considered that the viscosity index is based on the quality of the base oil and can be increased by additional additive packages (named as "VI-Improvers"). Group IV and V base oils automatically have a higher VI than those of Group I-III. The synthetic oils with a Group IV or V base oil also work with significantly fewer VI improvers despite a higher viscosity index, since their basic quality is better than that of hydrocrack oils.

Intermediate information: Pure mineral base oils usually have a viscosity index of around 95. The VI of synthetic base oils with additives, on the other hand, is already 130. 

➥ In short: The higher the viscosity index of the engine oil, the lower the change in viscosity at high temperatures.

High Temperature High Shear (HTHS)

The High Temperature High Shear (HTHS) describes the dynamic viscosity at 150°C and under the influence of high shear forces. Viscosity at high temperature and high shear rate (high speed range). Such conditions occur where mechanical components are subject to particularly rapid movements (e.g. crankshaft, cylinder track, etc.).

The HTHS value is shown in millipascal seconds (mPas). A higher value indicates a thicker oil film at high temperatures. This oil film would break later under these extreme conditions than those with a lower HTHS value. A higher value would therefore protect the engine more against wear, as the oil film remains permanent and guarantees lubrication. However, a lower HTHS value has the advantage that fuel savings can be achieved due to the lower internal friction and fewer exhaust gases.

HTHS limit values have also been defined in accordance with SAE and ACEA standards and several automotive manufacturers. They are intended to ensure that multigrade oils (e.g. 0W-30, 5W-30, etc.) with VI improvers (see „viscosity index“) guarantee the necessary lubrication despite extreme temperatures and shear rates.

Such limit values are structured as follows:

ACEA A5, B5: 2,9-3,5 mPas (low HTHS)

ACEA C2: ≥ 2.9 mPas (medium HTHS)

ACEA A3, B3: 3.5 mPas (high HTHS)

Vehicle manufacturers like VW, Opel, BMW, Mercedes Benz and Ford require a high or low HTHS value for their engines, depending on the engine type and oil approval. The HTHS value that an engine oil must have for its own vehicle is specified directly by the car manufacturer in the service manual. If an engine oil with the specification ACEA C2 is prescribed, no oil with an ACEA A5 / B5 specification should be selected, just because it has a lower HTHS value. After all, every engine needs a certain HTHS value for its optimum performance.

For this reason, the HTHS values between the oils can only be compared if they have the same specification(s). As mentioned above, an ACEA A5/B5 engine oil would always have a lower HTHS value than an ACEA A3/B3 engine oil.

In summary, it cannot be said whether a high or low HTHS value is better. This answer can only be given if, for example, the specified HTHS limit values (by standards such as ACEA, API, etc.) and the temperatures and shear forces occurring are taken into account.

In simple terms, if a car drives more short distances in urban traffic, lower temperatures and shear forces occur, a lower HTHS value would be advantageous.A fast driven car during long distances would, on the other hand, benefit from a higher HTHS value.

➥ In short: A comparison of these measured values can only be made if the engine oils have the same specifications or approvals and are therefore subject to the same tolerance intervals.

A higher HTHS value has a positive effect on engine protection at high temperatures and high shear forces (advantageous for driving at higher speed range and long distances). A lower HTHS value has a positive effect on fuel consumption and exhaust emissions at lower temperatures and shear forces.

Total Base Number (TBN)

The Total Base Number (TBN) describes the total number of bases inside of an engine oil. This value is particularly relevant for the analysis of the lubricant. The TBN value indicates the alkaline reserve inside of the engine oil. This value is represented in mgKOH/g.

The task of the alkaline reserve is to neutralise harmful acids which are produced by the combustion of sulphurous fuel.

Intermediate information: The sulphur content of the fuel is not the same in every country. The higher the sulphur content, the faster the alkaline reserves are consumed. As a result, the engine oil would have to be changed more often than in countries with low levels of sulphur in the fuel. In Germany, the proportion of sulphur in fuel is comparatively low.

The harmful acids ultimately lead to corrosion in the engine. The alkaline reserve, and thus the TBN value, decreases steadily over the lifetime of the engine oil. The higher the mgKOH/g in the engine oil, the longer the engine oil can protect the engine from the negative effect of harmful acids. As mentioned above, however, this duration of protection also depends on the respective sulphur content in the fuel.

➥ In short: The higher the TBN value (mgKOH/g), the longer the active engine protection against alkaline acids takes place.

Sulphate Ash

The portion of sulphate ash is the result of the combustion of engine oil. During engine operation, metallic abrasion occurs which is absorbed by the engine oil. In addition, other impurities, such as dust, can get into the engine oil.

In the laboratory test, the engine oil gets heated and annealed at a temperature of around 775°C - 800°C. The sulphur ash (represented in decimal numbers) in the form of remaining metal oxides and impurities is measured by its weight.

A high proportion of sulphate ash increases the risk of clogging the fine pores of the diesel particulate filters or the fins of the catalytic converter. To reduce this ash content, special LOW-SAPS engine oils have been developed. The proportion of additives such as sulphur, zinc, boron, magnesium, calcium and phosphorus has been reduced in these engine oils in order to reduce the sulphate ash content and relieve the exhaust aftertreatment systems. However, it must also be mentioned in this context that the reduction of additive packages also reduces the alkaline reserves (see TBN) and thus reduces the longevity of the engine oil. Due to this correlation, it becomes clear that the low or high contents of sulphate ash can sometimes have advantages but also disadvantages.

➥ In short: A low content of sulfated ash is better for the service life of the diesel particulate filter (DPF) and catalyst. However, it has a shorter service life of the engine oil (see „TBN“).

The following four properties (CCS, MRV, NOACK and Pourpoint) can be an indication of the used  base oil of an engine oil. A distinction is made between different groups of base oils. Groups I-III are mineral oils and hydrocracks (and thus semi-synthetic oils). Group IV and V are synthetic motor oils (PAO) which have fundamentally improved chemical properties.

Cold Cranking Simulator (CCS)

The cold viscosity determined with the CCS Cold Cranking Simulator is a characteristic value that indicates the cold viscosity at friction points (cylinder-piston group, wheel bearing, etc.). The limits are set by the SAE J300 standard. This method is used to simulate the dynamic viscosity of the oil during a cold start (the engine is started at low temperatures). The cold viscosity is measured in millipascal seconds (mPas).

As the temperature decreases, the viscosity increases. It means that the oil becomes more viscous. In order to correctly interpret the results from the CCS, it is always necessary to indicate the temperatures at which the test was carried out. In this oil analysis, a temperature of -35°C was measured.

As mentioned, the viscosity of the oil runs counter-rotating to the temperature. A decreasing temperature results in an increasing viscosity. The result from the table must therefore be interpreted as meaning that a lower value of the millipascal seconds (mPas) for the tested -35 degrees means a lower increase in the viscosity.

➥ In short: A lower value implies a lower increase in viscosity at cold temperatures.

Mini Rotary Viscometer (MRV) -40 degrees

The term MRV refers to the Mini Rotary Viscometer. It is a device used to measure the pumpability of an engine oil at low temperatures and a defined temperature profile. The test method used is ASTM D4684. The result is reflected in millipascal seconds (mPas). The engine oil needs this mPas for the oil supply. The results refer to a temperature of -40°C.

➥ In short: The lower the mPas of this analysis, the lighter and faster the engine oil is pumpable and can lubricate the engine at low temperatures.

Volatilization according to NOACK at 250 degrees

Evaporation according to NOACK at 250°C investigates the evaporation loss of the engine oil. An engine oil consists of various chemical components. These, in turn, have different volatilities and evaporate at different temperatures. This test examines the resistance of the oil to evaporation. The result is the thermal resistance of the engine oil.

In the NOACK test, the engine oils are heated to a temperature of 250°C and exposed to a constant air flow. Under these conditions it is measured which percentage of the oil evaporates within a time interval of 60 minutes.

➥ In short: the higher the percentage, the higher the evaporation and thus the evaporation of the engine oil.

Pourpoint

The pour point (measured in -°C) indicates the temperature at which the oil is still flowing. However, it says nothing about the flowability at low temperatures. For this reason, this measured value also plays a subordinate role with regard to the quality aspects of an engine oil.

With regard to flowability at low temperatures, it is more important to pay attention to viscosity. A multigrade oil, such as a 10W-40, must still have a prescribed flowability at -25°C. This is because the viscosity of a multigrade oil must be at least as high as that of a 10W-40. The same therefore applies to 0W-30 oils.

If there is a high pour point (the higher the temperatures below zero), the lower the temperature will be before the oil can no longer flow.

➥ In short: The Pourpoint is not a direct quality aspect of an engine oil and says nothing about the flowability at low temperatures. A higher pour point ultimately indicates the low temperatures at which the oil is still flowing.

Flash Point

The flash point is the temperature at which vapours generated by the temperature would ignite in combination with air. The higher the viscosity, the higher the flash point of the engine oil.

Intermediate information: The flash point does not affect the quality of the engine oil. This characteristic value is rather relevant when it comes to bearings or transport.

➥ In short: The higher the flash point, the higher the temperature would be needed to cause ignition in the engine.

Results of the oil analysis

All presented results of the 0W-30 oil analysis are also available in our compressed table. 

Oil Analysis PDF