Engine oil

Material mix of engine oils

The main characteristics of lubrication of any oil is based on the base oil as well as the physical limits of the oil.

The characteristics of oils can be improved with additives although this can also have a negative impact on some of the oils specification.

Mineral oils

The base of those oils is the raw oil. In order to get the characteristics of the raw oil to work with modern engines, additives are requires. Those additives will increase the flow stability, reduce foaming characteristics, cleanliness and more.

Semi synthetic oils

Synthetic oils are made of mineral oils but modified by synthetic processes in order to improve their characteristics.

Fully synthetic oils

These oils are fully syntactical created oils and do not base on mineral oils.

Additives

Additives are any additions to the oil that improve the characteristic of the oil. e.g.:

• Flow stability
• Wear
• Corrosion
• Cleanliness
• Coking
• Sludge protection
• Deterioration
• Oxidation
• Evaporation loss
• Filterability
• Foaming characteristics
• Flashing point

However, additives can also have a negative impact on the oil such as decreasing the HTHS.

HTHS - High Temperature High Shear

Since the F20C engine in the Honda S2000 is a very high revving engine, it is recommended to use an oil with a highest possible HTHS.
A higher HTHS means a lower fuel efficiency but a better lubrication during higher engine load/stress.
Experienced Honda S2000 drivers from various communities recommended to get an oil with at least HTHS > 4,0 mPas or higher.

Viscosity

Generally speaking there are single grade and multigrade oils. We will only use multigrade oils in our Honda S2000.
Multigrade oils will have a viscosity that is thin enough for cold temperatures while still having a viscosity that is thick enough for high temperatures.

The viscosity or flow of multigrade oils is described as e.g. “10W-30”.
The first number “10W” describes the viscosity at cold temperatures (-18°C). The “W” stands for winter.
The second number “30” describes the viscosity at hot temperatures (+99°C).

This means that a 5W-30 oil will be thinner on low temperatures while a 5W-40 oil will be as thin as the 5W-30 on cold temperatures but at the same time it will also be thinner on high temperatures.

ACEA / API Classes

Specifications are important as these indicate the performance of the oil and whether they have met or passed the latest tests or whether the formulation is effectively obsolete or out of date.
There are two specifications that you should look for on any oil bottle and these are API (American Petroleum Institute) and ACEA (Association des Constructeurs Europeens d’Automobiles).
All good oils should contain both of these and an understanding of what they mean is important.

API

S = Petrol, C = Diesel, although many oils carry both classifications.

• SA - Until 1930: Contains no additives. Not suitable for use in most gasoline-powered automotive engines built after 1930.
• SB - 1930: Used for engines with low performance. Contains additives against wear, corrosion and deterioration.
• SC - 1964: Used for engines with low performance. Contains additives against coking, sludge, wear, corrosion and deterioration.
• SD - 1968: Used for engines with higher performance that were produced between 1968 and 1971.
• SE - 1971: Used for engine with high performance and high requirements. Also applicable for “Stop-and-Go”.
• SF - 1980: Used for engine with high performance and high requirements. Exceeds the SE requirements in regards to oxidation, wear, sludge protection.
• SG - 1987: Used for engines with the highest requirements with special requirements regarding oxidation and sludge protection.
• SH - 1993: Corresponds with the SG requirements. Additional higher requirements for HTHS, evaporation loss, filterability, foaming characteristics, flashing point.
• SJ - 1996: Succeeder of API-SH. Higher requirements for evaporation loss and there for less oil loss.
• SL - 2001: Succeeder of API-SJ with higher requirements regarding deterioration, flow stability, efficiency, cleaning of the engine, wear (especially at higher oil change intervals).
• SM - 2004: Succeeder of API-SL with even higher requirements for oxidation stability, cleaning of the engine, wear, deterioration and performance at low temperatures.
• SN - 2010: Succeeder of API-SM with higher temperature protection, sludge prevention, sealing compatibility, better fuel efficiency, protection for turbochargers, compatible with exhaust gas purification systems, compatible with engine that use ethanol fuel.

ACEA

A = Petrol, B = Diesel and C = Catalyst compatible or low SAPS (Sulphated Ash, Phosphorus and Sulphur).

• A1 - Fuel economy petrol engines with low HTHS (<3,5 mPas)
• A2 - Standard performance level
• A3 - High performance and/or extended drain
• A4 - Reserved for future use in certain direct injection engines
• A5 - Combines A1 fuel economy with A3 performance

• B1 - Fuel economy diesel with low HTHS
• B2 - Standard performance level (now obsolete)
• B3 - High performance and/or extended drain. Exceeds B2 in regards to wear, cleanliness, flow stability and grime level.
• B4 - For direct injection car diesel engines (TDI)
• B5 - Combines B1 fuel economy with B3/B4 performance

• C1 - Petrol and Light duty Diesel engines with diesel particulate filter (DPF).Sulfating ash max. 0,5%. With lower HTHS.
• C2 - Petrol and Light duty Diesel engines with diesel particulate filter (DPF).Sulfating ash max. 0,8%, HTHS > 2,9 mPas
• C3 - Petrol and Light duty Diesel engines with diesel particulate filter (DPF).Sulfating ash max. 0,8%, HTHS > 3,5 mPas

Shelf life / expiry date of new oil

Oil producers test their oils for stability of at least 36 months. That means any oil is demonstrably fine to use within an age of 36 months.
This refers to closed oil containers! There is no guarantee once the container is opened.
Store your oil in dark and dry places at relatively low temperatures.

Mixing different oils

Generally you can mix fully synthetic oils.
However, it might lead to unknown results which is why it might not be the best solution.
You should never mix fully synthetic oils with semi-synthetic or mineral oils!

How to make sure no old oil is remaining / exchanging 100% of the old oil with new oil

• Do three oil changes in a row and if possible drive the car between each changing cycle for a short time.

This guarantees almost 100% that no old oil is left in your transmission/engine/differential and that it has been exchanged completely with new oil.
The same procedure is used by oil companies between test cycles in their R&D facilities.
You might want to do this when changing to a different type or brand of oil.

Reading the oil level dipstick correctly

One of the common faults when reading the oil level by using the oil dipstick is to remove the dipstick only once from the engine and go with the first reading of the dipstick. This causes two problems:

1. The dipstick will show to different oil levels, depending on which site of the dipstick you are looking at
2. There is a good chance that remaining excess oil will be on the dipstick

In order to get a correct reading of the oil level dipstick proceed like this:

1. Make sure the engine is warm since the oil will expand under heat
2. Position the car on an even surface
3. Turn off the engine and let it sit for about 10 minutes
4. Remove the dipstick and clean it with a paper towel. Repeat this step 3 times.
5. The 4th time you remove the dipstick, read the oil level from both sites of the dipstick. This will be your definite oil level.

OEM Specifications

• Fully synthetic oil
• 10W-30 for summer usage only (-20°C to +40°C)
• 5W-40 if also driven during the winter (-30°C to +40°C)
• API SJ or better (such as API SL or SM or SN)

Recommendations

Generally speaking you want:

• The highest possible flashing point
• The lowest possible pour point
• The lowest possible sulphated ash
• The highest possible total base number
• The highest possible HTHS

Throughout the experience of many S2000 communities and drivers the following engine oils seem to be recommended and to have gained positive feedback:

Mobil1 5W-50 (Rallye Formula, Peak Life, X1 FS)

Currently named "Mobil1 FS X1 5W-50" but previously also known as "Rallye Formula" and "Peak Life".
Oil analysis from other Honda S2000 drivers have shown that the oil is not too thick for the S2000 and that it's viscosity at @100ºC breaks down to 14,5 after very few kilometers of usage.
This essentially makes it a fitting oil with the advantages of a "thin" 5W-40 while retaining the capabilities of a "durable" 5W-50.

Further details and as well as oil analysis can be found in Mobil1_5W-50

Flash Point, ºC (ASTM D92)	239
Pourpoint, ºC (ASTM D97)	-45
Sulfated Ash, wt% (ASTM D874)	1.3
Total Base Number (ASTM D2896)	11,8
HTHS, mPa•s @150ºC (ASTM D4683)	4,5
Density, @15ºC, g/ml (ASTM D4052)	0,85
Viscosity, @40ºC, (ASTM D445)	101
Viscosity, @100ºC, (ASTM D445)	17,5
Viscosity index (DIN ISO 2909)	180
API	SL/SM/SN
ACEA	A3/B3, A3/B4

Motul 300V Power 5w-40

Flash Point, ºC (ASTM D92)	230
Pourpoint, ºC (ASTM D97)	-45
Sulfated Ash, wt% (ASTM D874)	n.a.
Total Base Number (ASTM D2896)	8,25
HTHS, mPa•s @150ºC (ASTM D4683)	4,1
Density, @15ºC, g/ml (ASTM D4052)	0,86
Viscosity, @40ºC, (ASTM D445)	81,8
Viscosity, @100ºC, (ASTM D445)	13,6
Viscosity index (DIN ISO 2909)	174
API	n.a.
ACEA	n.a.

AMSOIL Signature Series Synthetic 5W-30

Often recommended in the US.

Flash Point, ºC (ASTM D92)	220
Pourpoint, ºC (ASTM D97)	-50
Sulfated Ash, wt% (ASTM D874)	1,47 (?)
Total Base Number (ASTM D2896)	12,5
HTHS, mPa•s @150ºC (ASTM D4683)	3,11
Density, @15ºC, g/ml (ASTM D4052)	n.a.
Viscosity, @40ºC, (ASTM D445)	59,7
Viscosity, @100ºC, (ASTM D445)	10,3
Viscosity index (DIN ISO 2909)	162
API	SM/SN
ACEA	A5/B5

AMSOIL Signature Series Synthetic 5W-50

Seems to have better specifications than the 5W-30 version.

Flash Point, ºC (ASTM D92)	224
Pourpoint, ºC (ASTM D97)	-48
Sulfated Ash, wt% (ASTM D874)	n.a.
Total Base Number (ASTM D2896)	12,5
HTHS, mPa•s @150ºC (ASTM D4683)	4,45
Density, @15ºC, g/ml (ASTM D4052)	n.a.
Viscosity, @40ºC, (ASTM D445)	119,5
Viscosity, @100ºC, (ASTM D445)	19,4
Viscosity index (DIN ISO 2909)	185
API	SN
ACEA	n.a.

Liqui Moly Synthoil HighTech 5W-40

Flash Point, ºC (ASTM D92)	230
Pourpoint, ºC (ASTM D97)	-45
Sulfated Ash, wt% (ASTM D874)	1.0 - 1.6
Total Base Number (ASTM D2896)	10,5
HTHS, mPa•s @150ºC (ASTM D4683)	>= 3,5
Density, @15ºC, g/ml (ASTM D4052)	0,85
Viscosity, @40ºC, (ASTM D445)	90.2
Viscosity, @100ºC, (ASTM D445)	14,5
Viscosity index (DIN ISO 2909)	167
API	SM
ACEA	A3/B4

Castrol Edge 5W-40 (with red cap)

Flash Point, ºC (ASTM D92)	207
Pourpoint, ºC (ASTM D97)	-42
Sulfated Ash, wt% (ASTM D874)	0,8
Total Base Number (ASTM D2896)	n.a.
HTHS, mPa•s @150ºC (ASTM D4683)	n.a.
Density, @15ºC, g/ml (ASTM D4052)	0,85
Viscosity, @40ºC, (ASTM D445)	75
Viscosity, @100ºC, (ASTM D445)	13,0
Viscosity index (DIN ISO 2909)	174
API	SN
ACEA	C3