Smart Fortwo 450 CDI Oil Change — OM660 0.8L Turbodiesel
Service interval: Every 6,000 mi or 12 months. These engines are old — don't stretch this.
Tools you'll need
- Jack and jack stands (or solid ramps)
- Wheel chocks
- Drain pan (5L+)
- Cap-style oil filter wrench for the cartridge housing
- Socket set with the right hex/Torx for the drain plug
- Torque wrench (small range; 0-40 Nm)
- New crush washer for the drain plug
- Funnel with a long flexible neck
- Nitrile gloves and shop rags
Fluids & specs
| Fluid | Spec | Capacity |
|---|---|---|
| Engine oil — 450 CDI (OM660 0.8L turbodiesel) | 5W-40 low-SAPS, ACEA C3, MB 229.51 (or MB 229.31). The original spec was MB 229.1 and is hard to source today; 229.51 supersedes it cleanly for this engine. | ~3.5L with filter |
What this is + why it matters
The 450 CDI is the OM660 0.8L three-cylinder turbodiesel in the original Smart Fortwo body — built from 1998 through 2007 in Europe, and grey-market in North America. Most of these cars are over 18 years old now. That age is the single biggest variable in this job, more than oil spec or capacity or drain plug position.
Oil itself is cheap. What's not cheap on a 22-year-old turbodiesel is a stripped sump thread, a clogged DPF from the wrong oil spec, or a filter you can't source on a Saturday because nobody in North America stocks it. Most of this page is about getting those three things right. The actual procedure is the easy part.
This page sits underneath the parent oil-change guide and goes deeper on the things that are 450 CDI-specific. If you have a 451 CDI or any petrol Smart, the parent page is what you want.
What you'll need
The fluid spec is the part owners get wrong. The 450 CDI was originally specified for MB 229.1 5W-40, which is an older Mercedes approval that's effectively gone from the modern shelf. The clean modern substitute is MB 229.51 (low-SAPS, ACEA C3) in 5W-40. It supersedes 229.1 cleanly for this engine and it's what almost every reputable European supplier ships now. MB 229.31 is the same family and also fine.
Why low-SAPS matters: later 450 CDIs were fitted with a DPF (diesel particulate filter), and full-SAPS oil clogs DPFs. Some early 450 CDIs without DPF can technically run full-SAPS, but the safe default — the one that covers every variant of this engine without you having to verify by VIN — is low-SAPS C3 with MB 229.51 approval on the bottle.
Do not buy generic 5W-40 from a parts-store shelf. A jug labeled "5W-40 European formula" with no MB 229.51 approval printed on it is gambling. Get the real approval. Liqui Moly, Castrol Edge Professional, Mobil 1 ESP, Total Quartz Ineo MC3, and Shell Helix Ultra all have MB 229.51-approved 5W-40 SKUs that ship in 5L jugs.
Capacity is ~3.5L with a filter change. Buy a 5L jug; the leftover is your top-off supply for the next year.
Filter and crush washer — plan ahead. This is the grey-market reality in North America: the OM660 0.8L cartridge filter element and the drain plug crush washer often aren't on the shelf at any chain parts store. Source from a smart specialist, eBay UK, German parts houses (autodoc.de, kfzteile24, pkwteile), or smartmadness in the US. Order before you drain. Don't drain old oil on a Sunday morning hoping the local AutoZone has your filter — they don't.
A torque wrench is non-optional on this car. The sump is aluminium, the threads are old, and a heli-coil repair on a 22-year-old sump is real money.
Step by step
The procedure shape is the same as any oil change. The 450 CDI specifics are in the gotchas section. This is the sequence:
- Warm the engine. Five minutes idling, or a short drive home. Diesels take longer to drain than petrol engines — warm oil drains noticeably faster, and on this engine that matters.
- Lift and secure the car. Jack stands on the rated points, or solid ramps. Always chock the wheels. Never crawl under a Smart sitting on a single jack.
- Locate the drain plug and the filter. The drain plug is on the underside of the OM660 sump — the 450 sump is its own design, smaller and packaged differently from any 451 sump. The cartridge oil filter is in a housing on top of the engine; access it through the rear hatch with the plastic engine cover off.
- Drain the old oil. Position the pan, crack the plug loose with a socket, then back it out by hand the last few turns. Let it drain at least 15 minutes. Diesel oil is dirtier than petrol oil and the last bit of drain time is where the suspended soot ends up in the pan instead of in your engine.
- Swap the filter cartridge. Unscrew the housing cap, pull the old element, replace the O-ring(s) that ship with the new filter kit, drop the new element in, and torque the cap to spec (verify in the workshop manual for your year — typically around 25 Nm, but confirm).
- Reinstall the drain plug with a new crush washer. Snug, then torque to spec — typically around 20-25 Nm on this sump, but verify the value for your year in the workshop manual before you lean on the wrench. Aluminium threads do not forgive.
- Refill with the correct oil and capacity. Pour in roughly 3.0L, then check the dipstick before adding the rest. Overfilling a small turbodiesel is worse than running it half a quart light — excess oil gets pushed past the turbo seals.
- Run the engine and recheck. Start it, watch the oil pressure light go out within a couple of seconds, then idle for a minute. Shut it off, wait five minutes for oil to settle, check the dipstick. Top off as needed. Crawl under and look for any drips at the plug or filter housing.
There's no service-indicator reset on most 450s — the dash on this generation is simpler than the 451 or 453.
Common gotchas
- Use a torque wrench on the drain plug. The 450 sump is aluminium and the threads are old. Don't gorilla it — there's no benefit to over-torquing and the downside is a stripped sump and a heli-coil repair. Specs on the workshop manual; mid-20s Nm is the typical range for this plug.
- Filter and crush washer often need EU sourcing. Plan ahead. North America does not stock this filter at chain parts stores. Order before you drain.
- Get the oil approval printed on the bottle. MB 229.51 (low-SAPS C3) covers every 450 CDI variant safely. Generic shelf 5W-40 without the approval, or full-SAPS C2 oil in a DPF-equipped car, will eventually clog the filter and that's a much bigger bill than the right oil.
- The 450 CDI is not a 451 CDI. Different engine generation, different sump, different filter housing position. Procedures and torques from a 451 CDI guide do not transfer cleanly. If you're reading a write-up online, verify it's specifically the 450 CDI before you commit.
- Cars that have sat develop their own problems. A 450 that's been parked for months will often have a soft-seized alternator that prevents cranking — see 450 Alternator Soft-Seize. If you're servicing a car coming out of long storage, expect to chase down one or two other things at the same time as the oil change. Plan a half-day, not an hour.
- Glow-plug condition matters more than oil on a cold start. If the car cranks for several seconds before catching, that's not solved by fresh oil — that's a glow-plug job. Worth knowing before you blame the wrong thing for a hard-start complaint after the service.
- Timing belt history is the bigger ticking item. The OM660 in the 450 is an interference engine on a rubber belt. If service records don't show a belt + tensioner + water pump done at the OEM interval, that's a bigger priority than any oil change. See Timing Belt CDI — that page is written for the 451 CDI but the principle (interference engine, belt-driven, do everything together, shop job for almost everyone) applies to the 450 OM660 too. Verify your specific year's interval in the workshop manual.
- Don't skip the crush washer. A reused crush washer on a 22-year-old aluminium sump is how a clean oil change becomes a slow drip on the garage floor a week later. They cost a dollar. Buy a few.
- Dispose of the old oil properly. Most auto parts stores will take used oil for free. Diesel oil is darker and dirtier than petrol oil — that's normal, not a sign of a problem. Soot is what diesel oil does.
When to skip DIY
If you don't have a way to lift the car safely — jack stands on the rated points, ramps, or a lift — this is a job to outsource. Working under any car on a jack alone is how people get killed. Same goes if your driveway is sloped, if you can't dispose of used oil locally, or if you're not confident reading a torque wrench on aluminium threads.
The other reason to skip DIY on a 450 CDI specifically: if the car has been sitting and you suspect it has multiple issues, an experienced Smart shop can do the oil change as part of a broader recommissioning service and catch the alternator, belt, and glow-plug status in one visit. That's often better value than doing one job at a time on a car that needs several.
A shop oil change on a 450 CDI in Europe runs roughly EUR 80-130 if the shop has the right oil and filter on hand. In North America, expect to either ship parts to the shop yourself or pay a Smart specialist who already stocks them. Don't take a 450 CDI to a quick-lube — they will use the wrong oil, they will not have the cartridge filter, and they will probably refuse the job once they see the engine bay anyway.
Parts & typical prices
| Part | Typical price | Search |
|---|---|---|
| Oil filter cartridge (450 CDI / OM660) | $10-22 (often EU-sourced) | Amazon · eBay · AliExpress · Google |
| Drain plug crush washer | $1-3 | Amazon · eBay · AliExpress · Google |
| 5L jug of MB 229.51 5W-40 low-SAPS | $40-65 | Amazon · eBay · AliExpress · Google |
Prices are rough community-reported ranges, not quotes. Aftermarket vs. genuine Mercedes parts swing the spread. Marketplace links are non-affiliate.
Manual references
Top reference manuals for this chassis (from our catalog of 88 Smart manuals):
- 1998-2007 smart fortwo (450) - Communication & Breakdown Supplement — Breakdown Supplement, 33p, 2.3 MB
- 1998-2015 smart fortwo (450 451) - Technical & Service Reference — Technical & Service Reference, 977p, 92.7 MB
- 1999-2005 smart (450 452 454) - Glasurit Paint Color Codes — Paint Color Codes, 13p, 0.2 MB
- 2007-2014 smart (450 451 452 454) - Workshop Repair Manual — Workshop Manual, 4602p, 290 MB
- Fortwo 450-451 Owner Manual — Owner's Manual, 281p, 4.9 MB
Need something specific? Browse all 88 manuals by chassis, year, region, or document type.
