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Servicing guides and mods

Oil Specifications

There seems to be confusion over which oil can be used in the smart, luckily it happens to be very simple and covers all of the smart models.

Modification Details

Oil Specification

 There are three main types of oil:

Mineral based
Semi synthetic
Fully synthetic

You must use fully synthetic oil in your smart engine.

How Can I Tell If It Is Fully Synthetic?

It should state this info somewhere on the bottle, if it doesn't tell you in straight English that it
is fully synthetic then generally they are hiding something or trying to blind you with science.

Don't buy any engine oil which does not have the ACEA and API rating on the label.

MB229.5 Standards

Let me start off by saying, Mercedes Benz oil standards are pointless.

Firstly, they have only tested 1% of all of the oils available so even they don't know what oils are OK to use.

Mercedes used to sell Mobil1 oil because they were prime advertisers on the F1 cars. Mobil oils
aren't as good as people think, check out this independant test and see how badly it did.
Thankfully Mercedes realised how shit the Mobil1 oil was and changed their supplier to
Petronas. Even though Petronas also advertise on F1 cars, the oil is actually very good. 

So, as long as it's the right viscosity, is fully synthetic and has the API and ACEA ratings, it should be OK.

However, since the Mercedes oil is made by Petronas and is reasonably priced, you may as well buy it from them.

So, ALL smarts will use MB229.5 oil EXCEPT the 54bhp cdi 451 fortwo.

Can I Use MB229.51 In My Petrol Smart?

You can but it's really not good for your engine. The things that they take out to make MB229.51 oil are actually beneficial to the lubrication of the engine. Sulphated Ash, Phosphorous and Sulphur are good for the engine.

It's the anti-wear compounds added to the oil that contain most of the phosphorus and sulphur.

Anti-wear additives like ZDDP (Zinc Dialkyldithiophosphates) contains phosphorous,
MoS2 (Molybdenum Disulfide) contains sulphur and the detergent additives create sulphated ash when burnt.
Removing them creates a low SAPS oil that isn't as effective in protecting the engine as mid or high SAPS oil.

The oil companies are looking into replacement additives and detergents but what they currently
have just isn't up to scratch in comparison. However, as mentioned, you have no choice.

MB229.51 Standards

These standards are the one you need to pay attention to if you have the 54bhp 451 fortwo CDI.
Unlike the 45bhp model, the 54bhp has a DPF (diesel particulate filter) and absolutely requires MB229.51

The difference is that MB229.51 has low SAPS (Sulphated Ash, Phosphorus and Sulphur).
These damage the DPF by blocking it. So, low SAPS oil is essential.

Which Brand?

It doesn't really matter. For it to be classed as a fully synthetic oil at a particular weight (0W-40, 10W-30 etc) it has to pass tests and be within stated guidelines. People still feel better about using big brand names like Mobil1, Shell Helix and Castrol although Royal Purple seems to be way better in every way when it comes to engine wear.

Where Can I Buy The Best Oil?

The easiest way is to go to a smart dealer. However, you can buy it online too.


Mercedes MB229.5 Oil
Mercedes MB229.51 Oil (for 54bhp diesel)

Mercedes MB229.5 Oil
Mercedes MB229.51 Oil (for 54bhp diesel)

0W-40, 10W-30, What?

These pair of numbers are known as the weight. These tell you the viscosity (thickness) of the oil.
The first number is its cold viscosity, as the oil heats up it thins out allowing it to flow better.
The lower the number, the thinner the oil is.

The second number is the viscosity when at 212 Fahrenheit (100°C), 30 oil is thinner than 40 oil.

The W stands for 'winter' which is the thickness of the oil at 0° Fahrenheit (-18°C).
It is measured by the number of seconds it takes for a set amount to be pumped through
a tube of a particular size. This piece of aparatus is called a viscometer.

So What Oil Viscosity Do I Need?

It actually depends on the ambient temperature of where you live.

If you live in a very cold climate like Canada then you should consider 0W.
For us in England (which is a warm climate no matter what your Nan says) you are best off
with 10W (or 5W if you really have to). For the hot places like Spain, consider 15W or 20W.

Isn't 0W-30 Or 0W-40 The Best All Round?

No, they are really designed for use in cold climates and performance cars (smart cars don't
count no matter what BHP you claim). Lower W numbers give better cold starts that protect the
engine quicker as the lower temperature of the climate allows enough oil viscosity to cling to the engine
parts to protect them but also allows the oil to flow through the system at a reasonable pressure and speed.

Using 0W in a smart engine in anything but a cold climate will cause faster engine wear on cold starts.

Cold start damage happens in the 1st 10 seconds. It takes a smart engine 3 - 4 seconds to build up oil
pressure and another 3 - 4 seconds to properly coat everything, by which time, the damage is done.
Low viscosity oil drips off of all of the components when the car is standing. Higher viscosity oil
maintains a thicker film on all of the components so there is more oil there as the car starts.
The other issue is that the smart engine drains the majority of its oil back into the sump when the
engine isn't running. Within 10 minutes of standing, the turbo cartridge is empty of oil. This is bad
for the turbo when it starts up again as the shaft floats on oil bearings. Again, thicker oil leaves a
little bit more oil in the turbo to overcome the friction momentarily as the oil pressure build up.


450 & Roadster

If you live in the UK and have a smart of any description then use
5W-30, 5W-40, 10W-30 or 10W-40 oil.
I personally recommend 10W-40 for all 450s and Roadsters in the UK.

451 & Forfour Petrol

Mitsubishi make the petrol engines and they seem to recommend 5W-40 no
matter where you are. 5W-40 is fine unless you live in a VERY cold or VERY hot
country in which case go for 0W for cold and 10W for hot.

451 & Forfour Diesel

This is where smart start confusing things. The diesel engines are Mercedes units and
the fortwo diesel has the same engine in both the 450 and 451 variants. However, in
the 450 the recommend 10W-40 for UK temperatures but 5W-30 in the 451.

I have tried both of these in my 451 diesel and it was fine and I do a lot of miles.

For the Forfour, I'd stick with 10W-40 and vary that up or down for cold or hot countries.

Smart Recommended Oils

Smart published a list of acceptable oils for use in smarts to all their garages.
However, this does not mean that every oil below is suitable for your smart.
You should still use an oil designed for the environmental temperatures in your country.


Aral Supertronic G
BP Visco 7000 GM
Castrol DCO Topup
Castrol Edge
Castrol Formula SLX
Castrol Formula SLX Longtech
Castrol Syntec European Formula
Elf Excellium
Elf Excellium Full Tech
Gulf Formula Extreme
Pentospeed VS
Total Activia Energy 9000


Mobil 1
Mobil 1 Turbo Diesel


Addinol Super Power MV 0537
Adnoc Image
Agip Formula LL DC
Alpine Longlife
Aviaticon Unique DC
Divinol Syntholight MB
Elf Excellium 229.5
FormulaShell Ultra AB
Fuchs Titan Supersyn SL
Galax Syntec
Galp Formula XLD
Gulf Avantgarde K
Gulf Formula GX
Igol Process Compact P
INA Futura MB
Labo MB 229.5
Liqui Moly Longtime High Tech
Megol Motorenoel New Generation
Midland Crypto
Mobil SHC Formula MB
Motorex Profile M-XL
Motul 8100 X-Max
Motul Specific MB 229.5
OMV Full Syn MB
OMV Full Syn Plus
Panolin Exclusive BD


0W-40 is NOT the quickest way to protect your engine from cold start up.
So 'Paul' if you insist on saying I am wrong, at least have the balls to put your email address.
I said nothing about 'Race or track cars', I said performance cars.
Race and track cars require the least internal friction to release the most power from the engine.
These engines are also rebuilt every few thousand miles. The smart engine isn't.

Drawbacks Of Using Thicker Oil

You may see a marginal reduction in miles per gallon as there is slightly more resistance in the engine
whilst the oil is cold. When it reaches the preoper operating temperature, it'll be the same thinner oils.

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