Which oil does my car need?
0W-20, 5W-30, 5W-40 — what the numbers mean and why wrong-spec oil shortens engine life.
Your car was designed for one specific oil grade. Cheaper or thicker oil shortens engine life. Here’s how to read the label and pick the right one.
What the numbers mean
A typical modern grade is 0W-20 or 5W-30. Two numbers, separated by a W (for “winter”):
- First number (0W, 5W, 10W): how thin the oil is when cold. Lower = better cold flow at start-up. 0W is the thinnest commonly available.
- Second number (20, 30, 40): how thick the oil is at operating temperature (100°C). Higher = thicker at heat. 20 is thin (modern fuel-efficient engines); 30 is the most common; 40 is thicker (high-mileage or older engines).
Which grade does your car need?
- Modern petrol (Toyota Prius, Honda Civic Hybrid, Ford EcoBoost): often 0W-20
- Most European petrol/diesel (VAG, BMW, Mercedes 2015+): 5W-30 with a manufacturer spec like VW 504/507 or BMW LL-04
- Older European turbodiesels: 5W-40 with manufacturer-specific spec
- Older naturally-aspirated petrols (pre-2010): often 10W-40 or 15W-40
Always look at the handbook or the oil filler cap — never guess.
Synthetic vs semi-synthetic vs mineral
- Full synthetic: longer drain interval, better cold flow, better high-temperature stability. What most modern cars need.
- Semi-synthetic: older European cars, pre-2005 petrols. Fine if the manufacturer specifies it.
- Mineral: legacy engines, old farm machinery. Almost no modern cars use this.
Manufacturer-specific approvals
The grade (5W-30) is only half the story. The other half is the approval code:
- VW 504 / 507 — long-life VAG petrol/diesel from 2009+
- BMW LL-04 — most BMWs from 2007+
- Mercedes MB 229.51 / 229.52 — most Mercedes from 2008+
- Ford WSS-M2C913-D — Ford EcoBoost
- Toyota 0W-20 GF-6 / API SP — Toyota hybrids
Cheap supermarket “5W-30” without the right approval will technically lubricate the engine but may shorten DPF life or trigger fault codes. We always use the right approval.
What we charge
- Standard 5W-30 oil change: €75–€95 all-in
- Long-life 0W-20 / VW 504 / BMW LL-04: €95–€140
- Premium German V8 / V12: €150–€250 (8+ litres, expensive oil)
Book an oil change — phone 01 847 5146.