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Linkhttps://dev.evilution.co.uk/mod/servicing-a-54bhp-cdi-451.htm Copy to ClipboardThe servicing of the 54bhp diesel 451 is very similar to servicing all diesel smarts.
Glow plug change
Air filter change
Oil filter change
Cabin filter change
Oil change
The Important Difference
The main change is to the last point on the list, oil change. Although it is performed in the same manner as before, the oil you use must be a special type.
Magic Oil Huh!
Yep, this stuff is called low SAPS (Sulphated Ash, Phosphorus, Sulphur) oil.
It is very important for cars fitted with a DPF (Diesel Particulate Filter). The smart 451 54bhp diesel is the only smart with a DPF so it’s the only car you need to be specific when it comes to oil. Why? Click here.
MB Specification 229.51 & MB229.52
This is an addendum to the MB 229.5 oil specs for all other smarts. 229.51 & MB229.52 covers the oils necessary for DPF equipped cars.
The list of MB229.51 and MB229.52 oil plus other information can be found here.
What To Buy?
Most oil companies are creating low SAPS options anyway so it’s fairly easy to find. The price has risen from the MB 229.5 oil prices but we can expect this to go down. Oils that conform to MB 229.51 will actually state it on the container. Look out for it.
Why Does A DPF Need Low SAPS Oil?
What you may not know is that almost all engine oils are already fairly low in Phosphorus and Sulphur. These are the 2 elements that can serious damage a catalytic convertor. Since the CAT has been compulsory for a very long time, oil companies have reduced those significantly already.
So that’s the **PS dealt with, now on to the SA, Sulphated Ash.
DPFs aren’t mandatory but they may as well be. Without one, the car will not pass the Euro 5 emissions test which came into play 1st of September 2009. Sulphated Ash is a byproduct of combustion and this will irreparably block the mesh filter inside the DPF. Considering the cost of a replacement DPF or full replacement exhaust with DPF and CAT (in the case of the smart), it’d be a wise move to do anything not to block it up.
If it does block up, no amount of heating it will clear it out. Some cars fitted with CATs will pass an emissions test without one however, no cars fitted with a DPF will pass the emissions test if it is removed. So forget about replacing it with a pipe like you may with a CAT.
Is Low SAPS A Good Thing?
Not really, no. But you have no choice with the DPF equiped 451 CDI.
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.