APPROVED ENGINE OIL - MUST MEET MB APPROVAL 229.5

Approved Viscosities .................... 0W-40, 5W-40

Restriction: Only SAE 0W-40 and SAE 5W-40 engine oils meeting MB approval 229.5 may be used!


7.0L Capacity

We use LiquiMoly 5W40

 

Mobil 1 0W-40 Euro blend is what you want.

Bish

 

There is also a manual on your information screen

 

Reviving an old thread but was curious if there is any preference of using 229.5 or 229.51?

asking because when i got the service done by the dealer, they used 5w40 229.5 but now this indy shop has 5w40 229.51. Any problems with that or it doesnt matter?

 

Not an issue, You can safely run 5W-40 with MB-Approval 229.51 in the AMG GT R (M178), just as you can run 229.5.

For daily driving and moderate track use, there is effectively no downside.

For heavy, repeated track abuse, 229.51 simply carries slightly lower anti-wear additive reserves (mainly ZDDP) compared to 229.5, but it is still fully approved by Mercedes for this engine.



Let’s Get Technical:

What MB 229.5 and 229.51 Actually Mean?
Both MB 229.5 and MB 229.51 are Mercedes-Benz factory approvals, not marketing labels.
To earn these approvals, oils must pass high-temperature oxidation stability testing, piston deposit control testing, turbocharger coking resistance, shear stability validation, High Temperature High Shear (HTHS) minimum requirements and long drain interval durability testing.
For the Mercedes-AMG GT R with the M178 4.0L biturbo V8, Mercedes documentation (MB Sheet 223.2, attached) specifies 0W-40 or 5W-40, MB-Approval 229.5 or 229.51 (Western Europe) and 229.5 primarily for ROW markets

That means Mercedes engineering has validated both oils for the engine’s thermal and mechanical loads.

The Real Difference? SAPS Content

The only meaningful technical difference is that 229.5 is Full SAPS intended for performance focus and 229.51 is Low SAPS intended for emission system protection.

What is SAPS?

SAPS = Sulfated Ash, Phosphorus, Sulfur
These primarily come from detergents (calcium/magnesium) and anti-wear additives (ZDDP – zinc dialkyldithiophosphate)

ZDDP is critical in cam lobe protection, tappet interface protection and high-load boundary lubrication
229.51 reduces phosphorus slightly to protect Gasoline Particulate Filters (GPF) and catalytic converters.
However, both 229.5 and 229.51 still meet HTHS ≥ 3.5 mPa·s (or ≥ 3.5 centipoise, cP), which is probably one of the most important spec items for the M178 engine. Including severe turbocharger deposit control and AMG thermal requirements.

The M178 is closed-deck block, forged crankshaft, forged pistons, plasma-coated cylinder walls (NANOSLIDE), oil-cooled pistons and high-capacity oil system.
This engine is not “ZDDP sensitive” in the way flat-tappet classic engines are.

Track Use Considerations:
Under heavy track use, what matters most is oil temperature stability, shear resistance, film strength at 280°F+ and resistance to fuel dilution.
Both 229.5 and 229.51 5W-40 maintain similar HTHS values, similar viscosity retention and similar base oil quality (often Group III+ or PAO blends).
The only theoretical difference under extreme racing is the 229.5 may have slightly higher phosphorus reserve, hence, marginally more anti-wear margin under boundary lubrication conditions.

But this is measured in additive reserve, not in catastrophic protection differences.

Emissions & Catalyst Longevity:
If the car is stock, running catalytic converters and used on the street, 229.51 may actually be preferable long-term because of lower ash that reduced catalyst poisoning and has less particulate filter loading (if equipped).
Modern emissions systems are very sensitive to phosphorus contamination over time.

When I Would Personally Choose Each:
- Street-driven GT R: 229.51 is perfectly fine.
- Occasional track days: Either spec is completely acceptable.
- Frequent, high-heat, repeated track sessions (oil >280°F regularly): I would lean slightly toward 229.5 for additive reserve, not because 229.51 is unsafe, but because I prefer maximum anti-wear buffer in sustained boundary lubrication scenarios.

To conclude,
this is not a case of “right vs wrong oil.” Both 229.5 and 229.51 are factory approved, meet AMG durability standards, protect the M177/M178 architecture and are safe in 0W-40 or 5W-40 viscosities.

The difference is emissions optimization vs additive margin, not engine safety.

 

tyvm for such a detailed reply. one follow up from my side: if my car is tuned and has 200 cell sport cats, would one still be indifferent between 229.5 and 229.51 given that as far as i know sport cats wont have these particulate filters?

 

in this case personally I would go for 229.5 since it has slightly higher ash quantity (good to protect valve seats against hammering and no downsides considering you removed OEM cats)

 

It’s not so much about the tune itself, it’s more about how hard and how long you’re pushing the car, especially during extended sessions on a hot summer track day.

If you’re running repeated hot laps, high oil temps, and sustained high RPM under load, I would personally lean toward MB 229.5 for the slightly higher anti-wear additive package.
It’s not mandatory, but for prolonged, high thermal stress conditions, it offers a bit more margin.

On the other hand, aggressive driving on public roads (setting aside the police perspective ) is typically short bursts of load. From an engine oil standpoint, that kind of use is not a concern, regardless of whether the car is aggressively tuned or stock.
The oil simply doesn’t experience the same sustained thermal and shear stress as it does on track.

And yes, U.S.-spec AMG GT models do not have a gasoline particulate filter (GPF), so the Low SAPS requirement is not emissions-driven in the U.S. market.

 

Nice info but I was wondering whether the "oil >280°F regularly" was a typo and meant to be "oil >260°F regularly."

I've noticed that my GTR Pro starts pulling power at about 124 deg C (~255 deg F) and by about 127 deg C (260.6 deg F) it's down about 50 HP. You can readily hear it in the less aggressive and slightly lower RPM up-shifts.

280 deg F would be 137.8 deg C and I thought "red" status was at 135 deg C (or is it 130 deg C) so I can't imagine getting the oil up to that temp.

For me, when I've done a track day where the oil temps have gotten around 125 deg C, I will pull 4-5 L of oil from the tank and replace it with fresh. The idea being that the high temps will tend to degrade the oil additives more quickly so swapping 40+% with fresh oil will help keep the additives "up to snuff."

 

First, the idea of pulling oil and replacing 40%+ during or after high-load track sessions is a good practice. It helps restore oil properties that may have degraded due to heat, shear, or contamination.
Unfortunately, this is not easy for most non-professional drivers to do at a track garage.

Second, you are right about the HP drop. Cars like the Mercedes-AMG GT R Pro or Nissan GT-R have strict thermal management programming.
When the ECU sees oil or coolant temperatures cross ~255°F (124°C), it intentionally pulls ignition timing, reduces turbo boost, and limits throttle response to prevent the engine from melting itself.
That doesn't mean the internal parts are running at 255, they are probably higher. The oil actually inside the spinning rod bearings or turbochargers can be 30°F to 50°F hotter than what the gauge reads due to extreme localized friction and shear.

So why use 280°F as a reference point? It relates to the viscosity of 5W-40 oil under track conditions and when additives start to kick in.. We need to look at it from the engine oil POV
At 260°F, the oil is still hot but operating within a comfortable oil film thickness margin. At 280°F, that margin begins to shrink more noticeably.
280°F is not a failure temperature; it is a point where film thickness decreases faster, oxidation accelerates, anti-wear additives (like ZDDP) are more heavily engaged, and shear stability becomes critical.
Occasional spikes above 280°F are generally not a concern.

Engine oil operates across three lubrication regimes. In the hydrodynamic regime, a full oil film completely separates metal surfaces. In the mixed regime, the film partially separates surfaces, and in the boundary regime, anti-wear additives prevent metal-to-metal contact.

As temperature rises, viscosity drops.
For example, 5W-40 oil at 212°F (100°C) typically measures ~13–14 cSt. cSt (centistokes) is a unit of kinematic viscosity, which quantifies how fast a fluid flows under gravity: 1 cSt = 1 mm²/s. So 13.5 cSt means the oil flows at 13.5 mm² per second at the test temperature.

At 280°F (~138°C), the same 5W-40 oil may drop to ~7 cSt, roughly half its nominal viscosity. At this point, engine protection relies heavily on HTHS viscosity, additive chemistry, and the oil’s ability to maintain film under high shear conditions.

 

Exceptional write up, as per usual.

Regarding Mobil 1 *FS* European Car Formula, USA stock, and comparing 0W-40 vs 5W-40:

Given manufacturer's specs with noted Kinematic Viscosity and High-Temperature High-Shear KV of 0W-40 (13.8 @100C, 3.6 @150C), vs the 5W-40 (13.2 @100C, ?3.7 (i think) @150C), among other differences. . .

Ultimately, which weight (with their inherent different oil content and possibly slightly ?different additive package) will offer best protection under highest duress/load (typical Track loads) over the long term?

 

Thank you and...great question, and this is exactly the right way to compare oils: not by the front label, but by the actual viscosity data.

For full disclosure, this is not my direct area of expertise, but I did spend time reviewing the technical data and relevant lubrication principles to collect solid supporting facts.
Based on that research, here is my conclusion to your question.

To do a proper comparison, we need to consider the engine and the duty cycle. For the M178 in a GTR, the relevant use case includes high cylinder pressure (especially if tuned),
twin turbochargers with very high shaft speeds, large rod journal loads under boost, oil temperatures often in the 260–285°F range on track, and tight bearing clearances typical of modern AMG tolerances.
This is not a mild-duty environment.

Mobil 1 FS 0W-40 vs 5W-40:

At 212°F (100°C):
0W-40 KV ≈ 13.8 cSt
5W-40 KV ≈ 13.2 cSt

At 302°F (150°C, the HTHS test temperature under high shear conditions):
0W-40 ≈ 3.6 mPa·s
5W-40 ≈ 3.7 mPa·s

The difference looks small. However, in a boosted engine, bearing load increases disproportionately with boost.
Cylinder pressure increases rod bearing load much more than RPM increases hydrodynamic support.
That makes HTHS viscosity especially important, since it better reflects oil behavior in highly loaded journal bearings than KV100 alone.

From a rod bearing perspective at 7,000 RPM, higher surface speed helps maintain hydrodynamic film at redline.
However, peak torque in the midrange under boost often imposes higher bearing load than redline operation.
In a tuned GTR, increased boost increases combustion force, increased combustion force increases bearing load, and increased load reduces minimum oil film thickness.

Oil film thickness in a hydrodynamic bearing scales approximately with viscosity and inversely with load.
Even a ~3% difference in HTHS can become meaningful when margins are shrinking at 280°F.
In that scenario, the 5W-40’s slightly higher HTHS provides a small but real mechanical advantage under peak load.

Shear stability under sustained track use is where the difference can become more relevant.
A 0W-40 spans a wider viscosity range. To achieve both 0W cold performance and a 40-grade hot rating, formulators typically use more viscosity index improvers (although exact formulations vary).
Under sustained 280°F oil temperatures, high shear in rod bearings at 7,000 RPM, and repeated turbo heat cycling, viscosity loss can occur due to mechanical shear, oxidation, and in some cases fuel dilution.

Modern Mobil 1 0W-40 is very shear stable, but historically 0W-40 formulations tend to show slightly more viscosity reduction after repeated severe track sessions compared to 5W-40.
A 5W-40 often requires fewer viscosity index improvers and may retain viscosity marginally better over time.
For repeated hot track days, long-term viscosity retention can matter more than the fresh oil spec sheet numbers.

Turbochargers are particularly demanding on oil. They operate at extremely high shaft speeds, rely on very thin hydrodynamic films, and expose oil to high localized temperatures.
The difference between 3.6 and 3.7 HTHS is not dramatic in isolation, but stability under sustained thermal stress becomes relevant.

If oil temperatures are controlled under approximately 270°F, both oils perform very similarly.
If the engine regularly sees sustained 280–290°F oil temperatures, the 5W-40 gains a modest durability margin.

From a cold-start versus track optimization perspective, if the car sees winter use, is driven year-round, and only occasionally tracked, 0W-40 remains an excellent all-around choice.
However, if the car is primarily a warm-weather performance car, sees repeated heavy track sessions, runs elevated boost, and frequently experiences 275°F+ oil temperatures, 5W-40 becomes slightly more optimized for that duty cycle.

This is ultimately a margin discussion, not a survival difference.
Both meet MB 229.5. Both are approved. Both are high-quality oils.
But if the goal is maximizing protection margin under sustained high boost and elevated oil temperatures, 5W-40 is the slightly more conservative track-oriented choice.




Mobil 1 FS European Car Formula 5W-40 – Engine Bay ID Labels (Set of 2) | eBay