Choosing the brand of Engine Oil appears to be a religious decision for some.  Not just Aston Martin owners, but with car enthusiasts everywhere.  From Mobil 1, to Motul, Castrol, Royal Purple, and even generic cheapo brands the forum discussions run the gamut hot and heavy.   I take a more pragmatic approach to it – What does Aston say is best for it?  In this article I’ll take you on a quick FACT based tour of the requirements for the V12 engine (note this is not the same for the V8’s in the Vantage).  If you want the short version to skip the reading, just use Mobil 1 0W-40 like Aston recommends.  Read on for the why….

Aston Martin Oil Recommendations

If you want to know what Aston Martin recommends for the engine oil in your car, just reach over and open your glove box and refer to the Fluid Specifications page of your owners manual.   In my 2005 Aston Martin DB9 it looks like this:

Thinking that there might be even more to learn in the Official Aston Martin Workshop Manual Section 3.02 on Lubrication, the spell out the requirements clearly here as well:

Fortunately both things agree and are quite clear.  To reiterate:

Brand: Mobil 1

Viscosity:  0W-40 (0W-30 in cold climates)

It goes on to state “An oil of 0W-30 viscosity that is equal to Aston Martin specification WSS M2C913-A/B or 0W-40 viscosity that is equal to Aston Martin
specification WSS-M2C937-A is recommended. Where this is not
possible, oil that is equal to the following standards can be used.”

• API (American Petroleum Institute)  Here is a link to there standards guide
  •  SL (suitable for cars 2004 and older)
    • The API standards read that the ‘L’ standard is at least as good or better than any previous S standard like SJ.  As of this writing (2021), the SP standard has been introduced.
  • SJ (suitable for cars 2001 or older)
    • So Aston says that at least SJ, but as noted above SL is even better.
  • EC
  • CF
    • They describe this standard as suitable for Diesel engines
• ACEA  (Here is a link to learn about the standard)
  • A3/B3/B4
• ILSAC (Here is a link to the standards)
  • GF3 (and if you follow that standard link, it now says that its obsolete and to use GF5 or the newest GF6a standards.  Essentially something meeting the later standards is equal or better than the GF3)

What do those specs mean?

Aston Martin clearly spells out that the recommendation is to use Mobil 1 0W-40.

The oil must meet Aston Martin specification WSS-M2C937-A.  This is a technical engineering document that spells out all the nerdy details of the oil.  If you lookup that spec, you’ll discover that is Ford specification WSS-M2C937-A.  Remember, Ford owned Aston Martin when the DB9 and Vantage were designed.  Their engineers worked along with Astons to design the engine.  They know it best.

They go on to say that if you can’t find Mobil 1 or an Oil spelling out exactly that it meets the Ford WSS-M2C937-A standard, you can find an oil that meets all of these specific industry wide standards like the API Standards SL, SJ, EC and CF.

Mobil 1 0W-40 Specs

Since Aston clearly recommends Mobil 1 it will be worth checking out all we can learn about it.  Mobil 1 is a premium Full Synthetic oil. Its interesting to note that at least in the USA we are looking for Mobil 1 ‘European Formula’.    You can’t really go wrong since the only version of 0W-40 in the USA is the European Formula.  I looked up the Product Specifications for Mobil 1 0W-40 (view the official document here).

Property
Grade	SAE 0W-40
Kinematic Viscosity @ 100 C, mm2/s, ASTM D445	12.9
Pour Point, °C, ASTM D97	-60
Density @ 15 C, g/cm3, ASTM D4052	0.846
Kinematic Viscosity @ 40 C, mm2/s, ASTM D445	71
Flash Point, Cleveland Open Cup, °C, ASTM D92	226

Meets or Exceeds the Requirements of

AAE (STO 003) Group B7

API SJ

API SL

API SM

API SN

ACEA A3/B3

The Product Specification then has API SN (which supercedes the original SL/SJ requirement) and also meets the ACEA  A3/B3 standard.

Manufacturer Approvals

MB-Approval 229.3

MB-Approval 229.5

Nissan Genuine Performances

Porsche A40

VW 502 00

VW 505 00

Recommended for Use in Applications Requiring

API CF

FIAT 9.55535-M2

VW 503 01

How do other brands stack up?

I’m not an oil brand zealot.  I will spend a little more for a premium brand for a premium car, but I am not going to guess that something is better just because of advertising.

From the chatter on the Forums and Facebook Groups, it’s clear that many talk highly of the Motul brand.  I rely on Motul for the brake fluid in my DB9, so I’d probably consider it for my Oil too if necessary.

Without an exhaustive investigation it looks like Motul 8100 X-max 0W-40 is the competitive equivalent to the Mobil 1.  It also meets API standard SN and ACEA A3/B3.

I also use Castrol Edge full synthetic in several of my family’s cars and believe its a fine product as well.   It looks like Castrol Edge Euro 0W-40 meets API standard SN and ACEA A3/B3 and A3/B4, it exceeds ISLAC GF-6 and perhaps more importantly spells out that it meets the required Ford standard WSS-M2C937-A.  That’s convincing in my books.

But – even after looking at the standards they meet, they aren’t the exact same.  If you compare the Kinematic Viscosity 100°C of the Mobil 1 versus the Castrol Edge (find the product data sheet here), its 12.9 mm2/sec vs. 13.2.   Not the same.  So which is better?  I don’t know and unless you were an Aston Engineer during engine design and development you likely don’t know which would be better for the V12 either.  So why mess around and gamble?

Costs

Always a factor in some way, so I figured I’d take a look at how much a 5 liter bottle of each costs:

• Mobil 1 0W-40 5 liter bottle – $24.97 USD on Amazon with free shipping
• Castrol Edge 0W-40 5 liter bottle – $24.77 USD on Amazon with free shipping
• Motul X8100 X-max 0W-40 5 liter bottle – $52.53 USD on Amazon with free shipping

The Mobil 1 is essentially one of the least expensive options, identical to the Castrol.  The Motul is TWICE as expensive!   I don’t see any reason not to choose the Mobil 1 unless you can’t get it where you live, and then my second choice would be the Castrol Edge.

Aston1936 Recommends

I am certainly aware that Aston recommends Mobil 1 probably because Ford had a contract with them, so that’s the oil the developed the car for.   But that counts for something.  The engineers did all the testing with that oil, and it’s a guaranteed correct choice.  Its also a premium quality oil that is available generally globally at a reasonable price.

To me the choice is plain and simple.

If Mobil 1 0W-40 is available to you – use it.

My number two choice would be Castrol Edge Euro 0W-40 if I couldn’t get the Mobil 1.  After that, any quality brand full synthetic that meets or exceeds API standard SL.

What about Mixing Brands and Grades?

One last thought.   If you are on a road trip and discover you are a liter down, will it be a disaster to mix brands and even grades?   Not really.   If you normally use Mobil 1 0W-40 and have to stop and add a liter of Castrol Edge 5W-30 to continue your trip – don’t sweat it.   There are about 11 liters of oil in a DB9 V12, so adding 1 liter of something isn’t going to skew the deal much.

BUT, I would strongly recommend that you stick to full Synthetic oils, and not mix Synthetic and Conventional oils.  In a pinch to get home I would if I had no option, but I’d plan an oil change upon return.

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What do you use?

Its always interesting to see what others are using, so I’ve put together this quick poll if you’d take a second and check off which Engine Oil you are using.

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Video

If you’d like to see me expound on the topic out loud, plus see me interview Mike from Bamford Rose on his opinions as well, check out this video here.