| Table 1 | ||||||||||
| ACEA 2022 LOW (Low ) SAPS oils | ||||||||||
| High SAPS | Low SAPS | |||||||||
| Average SAPS | Average SAPS | Average SAPS | Average SAPS | |||||||
| A3/B4 | A5/B5 | C1 | C2 | C3 | C4 | C5 | C6 | |||
| Sulfated ash | SA | % | >1,0 < 1,6% | <1,6% | <0,5% | <0,8% | <0,8% | <0,5% | <0,8% | <0,8% |
| phosphorus | P | % | report | report | <0,05% | >0,07 < 0,09% |
>0,07 < 0,09% |
<0,09% | >0,07 < 0,09% |
>0,07 < 0,09% |
| Väävel | S | % | report | report | <0,2% | <0,3% | <0,3% | <0,2% | <0,3% | <0,3% |
Oil companies use the term Mid SAPS, which can be confusing.These Mid SAPS oils are still in the low SAPS family.
The main difference is that the sulphated ash level is in the mid-range compared to the so-called high SAPS oils.
Table 1: Of the six oils in the low SAPS family, the medium SAPS oils are C2, C3, C5 and C6 - comparing the sulphated ash limits with the high SAPS A3/B4 and A5/B5.
Transition to High Temperature High Shear (HTHS)
See Table 2
| Table 2 | |||||||||
| High Temperature High Shear (HTHS) | |||||||||
| High SAPS | Low SAPS | ||||||||
| Average SAPS | Average SAPS | Average SAPS | Average SAPS | ||||||
| A3/B4 | A5/B5 | C1 | C2 | C3 | C4 | C5 | C6 | ||
| HTHS | CentiPoise | >3,5 Cp | >2,9 <3,5 Cp | >2,9 Cp | >2,9 Cp | >3,5 Cp | >3,5 Cp | >2,6 < 2,9 Cp | >2,6 < 2,9 Cp |
High Temperature High Shear (HTHS) is the viscosity of an oil when tested under extreme stress or shear conditions and is designed to replicate the hostile conditions of the camshaft, valve train, piston rings and cylinder liners.In fact, anywhere in an engine where oil is forced through a very small opening, the oil can temporarily or permanently lose its proper viscosity.
HTHS is tested at 150c, but ACEA 2022 ranges test HTHS at both 150c and 100c.
The big thing about HTHS is that it's a path to greater fuel economy - and all carmakers have made fuel economy and emissions reductions their obsession in 2022. This is why C5 and C6 oils tend to be associated with low viscosity fuel efficient 0W-20.The obvious question is….does reducing HTHS viscosity affect engine wear?The answer is that the car manufacturers know how to design their very fine engine and we have to trust their expertise in this field and the oil companies are happy to mix C5/C6 oils.
The development team of one major oil manufacturer has highlighted the specific production problems of C5 and C6 oils.
A very high quality base oil with a boosted additive package is required to protect the engine from dropped HTHS.Oil chemists then apply their skills to ensure the finished oil is fit for purpose and provides a high level of engine protection.With this in mind, it pays to choose C5 and C6 oil wisely from oil companies approved by the manufacturer.
One important note is don't use low HTHS oil in an engine that isn't designed for it.
Looking at Table 3.
| Table 3 | |||||
| Do not use C5 or C6 oil when C3 oil is required | |||||
| C3 | C5 | C6 | |||
| HTHS | CentiPoise | >3,5 Cp | >2,6 < 2,9 Cp | >2,6 < 2,9 Cp | |
Using a lower HTHS C5 or C6 oil in an ACEA C3 application will result in an expensive engine rebuild.
Why?As a motor designed with a high film strength of 3.5 centpoise (cP) is given a low film strength medication in the range of 2.6 < 2.9 centpoise, motor wear problems occur.
One way to visualize what's going on inside an engine is to imagine that all the engine parts are floating on oil. If this buoyancy is interrupted, wear and engine damage can occur.Remember that 70% of engine wear occurs when the engine warms up.The big advantage of modern engines is - Always use the correct SAE viscosity grade, ACEA specification and most importantly - the correct manufacturer specification - and choose a quality oil with a balanced additive package.
In Table 4, we see the ACEA fuel economy standards.C5 and C6 oils lead the way in the pursuit of greater fuel economy.In addition, we are introduced to the so-called evaporation loss test.
Evaporative loss is an interesting topic.If the engine oil is low, there are only three places where the oil could have gone.A cloud of smoke from the exhaust pipe, an oily puddle on the ground, or the oil has evaporated due to the heat of the engine.Named after Kurt Noack, the Noack Volatility Test tests for this last cause of low oil.The oil is heated at 250c for an hour and for most oils apart from C4 the allowable loss is 13%.
However, car manufacturers often set stricter pass levels for manufacturer-approved oils.
| Table 4 | ||||||||||
| Fuel economy and evaporative emissions (Noack) | ||||||||||
| High SAPS | Low SAPS | |||||||||
| Average SAPS | Average SAPS |
Average SAPS | Average SAPS | |||||||
| A3/B4 | A5/B5 | C1 | C2 | C3 | C4 | C5 | C6 | |||
| Fuel consumption | MB engine M111 | % | —- | >2,5% | 3% | 3% | >1,0%, nt 5W-30* | >1,0%, nt 5W-30* | >3% | coming up |
| Evaporation loss | Noack | % | <13% | <13% | <13% | <13% | <13% | <11% | <13% | <13% |
Back to our original question - why do we need another Low SAPS oil?One reason is that ACEA 2022 has developed three very specific additional tests for C6 oil.
See Table 5 below.
Turbocharger Compressor Deposit (Diesel)
Automakers need to reduce emissions, and one way to do that is by increasing the level of Exhaust Gas Recirculation (EGR).The downside is that more soot can build up in the engine oil, which can deposit in the turbocharger's compressor housing.This leads to a reduction in compressor efficiency and subsequent engine performance.A Toyota 3L diesel turbo engine is used to test soot accumulation in turbochargers.The engine runs for 100 hours at full load at 3600 rpm.Turbochargers can run at 1000c and over 250,000rpm.It is very demanding on engine oil.It takes all the experience and skill of the major oil manufacturers to make the oil meet the requirements of this test.
Low speed pre-ignition system (LSPI)
This is a modern phenomenon of gasoline direct injection (GDI) turbo engines.We used to know it as detonation, pinky or pre-ignition.It has re-emerged in recent years and can wreak havoc on an engine by making spectacular holes in the pistons.
The test uses a Ford four-cylinder gasoline engine
The last specific C6 test is timing chain wear
Timing chain elongation or stretch is measured to ensure valve timing.Ford's 2.0L EcoBoost engine is also used in this test.The engine runs for 216 hours through a series of cycles.The pass/fail criterion is ≤0.085% of timing chain elongation.
| Table 5 | |||
| ACEA C6 | |||
| Turbocharger Compressor Deposit (Diesel) | Toyota engine 1KD-FTV | Value | >25 |
| Low speed pre-ignition LSPI (GDI turbo) | Ford GDI engine (Gasoline direct injection) |
LSPI attempts | <8 |
| Chain wear GDI (Gasoline direct injection engines) |
Timing chain extension Ford GDI engine (Gasoline direct injection) |
% | <0,085% |
ACEA C6 oil example SynPower MST FE C6 0W-20.Valvoline has combined the chemistry with ACEA C5 to provide a greater range of applications.
ILSAC GF-6A and API SN Plus test oils for low speed pre-ignition (LSPI) resistance.
Coming back to the Norma from Bristol, you can be sure that as emissions standards improve, there will always be "another" with an ACEA standard term shorter than the average prime minister's tenure.Anyone involved in vehicle maintenance cannot be expected to know everything about every oil.
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