I had my oil replaced and they put in Mobil Super 3000 5W-40. The manual says "with Multi Air systems using lubricants with features lower than ACEA C3 and SAE grade other than 5W-40 could cause engine damage". The spec for the oil used says it meets:

ACEA A3/B3, A3/B4 
AAE (STO 003) Group B6

So no mention of ACEA C at all.

What should I do? The warning seems stern though the wording is odd, 'and' implying that the oil has to be both non ACEA C3 compliant and not 5W-40 to cause trouble, but it is probably just a sloppy writing, and they meant 'or' instead of 'and'. Should I change the oil asap or is it benign? The guys at the service are not changing oil since yesterday so perhaps that is not that big of a deal?

The engine is 1.4 Multi Air: a turbo charged petrol engine from Fiat.

  • Welcome to Motor Vehicle Maintenance & Repair! Commented Aug 26, 2018 at 17:56
  • So what does or does not C3 have compared to A3/B3 and A3/B4?
    – Solar Mike
    Commented Aug 26, 2018 at 17:57
  • 2
    C3 is "catalyst compatible." A3/B3 is not. oilspecifications.org/acea.php. I would tell the garage you want the job done right, and at their expense. (And next time you need an oil change, go some place else!)
    – alephzero
    Commented Aug 26, 2018 at 19:38

1 Answer 1


C3 means Low SAPS. It's meant to be even more compatible with Three Way Converters and Diesel Particulate Filters, since sulphated ash, phosphorous and sulfur can reduce the efficiency of these exhaust treatment devices (the catalyst, for example, can be poisoned). Since some oil always ends up burned by the engine even if you can't see any blue smoke and you don't see the oil level decrease, if you want to prolong the converter's life, use C3 oils only, especially if the manufacturer said to only use oils with such a specification. Yes, the oil should be changed immediately. Try showing whoever put that oil in the relevant page of the car's manual. He/she will hopefully immediately realize the mistake done, especially if you have a receipt which shows that the car was serviced with the wrong type of oil.

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