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The Complete Engine Oil Spec Guide

Make sense of every number and approval on an oil label: SAE viscosity, API / ACEA / JASO / ILSAC, industrial ISO VG, diesel Low SAPS & DPF/SCR, and heavy-duty EURO 3–6 — then use one table to pick the right oil by vehicle. Written by Taiwan lubricant manufacturer ONEWAY.

In one minute

TL;DR

5W-40Number before W = cold-flow (lower = better cold start); after = high-temp film (higher = thicker)
API/ACEAUS / EU grades; the ACEA C series is Low-SAPS, DPF-compatible
JASOMotorcycle only: MA2 = wet clutch (geared), MB = scooter
Manual firstAlways follow the viscosity & spec in your owner's manual
Lesson 1

How to read SAE viscosity (what 5W-40 means)

A grade like "5W-40" has two numbers: the figure before W (Winter) is cold-flow — lower means thinner, faster cold starts and better low-temp protection; the figure after is the oil-film strength at 100°C — higher means thicker and stronger high-temperature protection.

GradeCharacterTypical use
0W-20Thinnest, most fuel-savingJapanese new cars, hybrids
5W-30Balanced economy & protectionMost modern petrol cars
5W-40Strong high-temp filmEuropean, turbo, performance
10W-40 / 10W-50Thicker, heat-tolerantHigh-mileage, hot climates, bikes
15W-50 / 20W-50Thickest, strongest filmOlder engines, heavy load, track
Lesson 2

Specifications & approvals

Viscosity only describes thickness; specifications describe quality and which engines an oil suits. Here are the most common standards.

API (American Petroleum Institute)
Petrol grades start with S (SN, SP…), diesel with C (CI-4, CK-4…); later letters are newer, with SP the current top petrol tier.
ACEA (European automakers)
A/B = general petrol/diesel, C = Low-SAPS (DPF/catalyst compatible), E = heavy-duty diesel. European cars usually require an ACEA spec.
JASO (Japanese motorcycle)
For 4-stroke bikes: MA/MA2 = wet clutch (geared bikes, prevents slip), MB = scooters. The wrong one causes clutch slip or judder.
ILSAC (US/Japan economy)
e.g. GF-6, emphasising fuel economy and protection; usually shown alongside API SP, common on Japanese cars.
ISO VG (industrial oils)
Industrial oils (hydraulic, gear, compressor) use VG 32/46/68/220…; the number is kinematic viscosity at 40°C — higher is thicker.
OEM approvals (MB, VW, Porsche, BMW…)
e.g. MB 229.5, VW 504/507, Porsche A40 — a carmaker's formal approval of a specific oil, the most direct proof of quality.
Lesson 3

Low SAPS, DPF & SCR

Modern diesels (and some petrol cars) have a DPF particulate filter or SCR catalyst. The sulphated ash, phosphorus and sulphur (SAPS) in ordinary oil can clog or poison these systems, so they require Low-SAPS oil — meeting ACEA C (C2/C3) or heavy-duty ACEA E6/E9. Using the wrong high-SAPS oil on a DPF car can clog the filter and lead to costly repairs.

Lesson 4

Heavy-duty diesel oil & EURO 3–6

Heavy-duty diesel vehicles (trucks, buses, construction equipment) use different oil tiers depending on their EU emission stage (EURO 3 to 6).

StageAfter-treatmentOil focusONEWAY match
EURO 3NoneHigh TBN, anti-wear, long mileageONEWAY HDDO EURO 3
EURO 4No DPFHigh-temp film, oxidation controlONEWAY TURBO EURO 4
EURO 5 / 6DPF / SCRLow SAPS, after-treatment safeONEWAY ECO EURO 5/6
In practice

Quick oil selection by vehicle

Putting it together — recommendations for common vehicles. Can't find your grade? Ask us and we'll help you choose.

Vehicle / useViscosityKey specRecommended
Japanese new cars · economy0W-20API SP · ILSAC GF-6MegaTec 0W-20
European high-performance petrol5W-40MB 229.3 · Porsche A40Max Evolution 5W-40
European diesel (with DPF)5W-30ACEA C3 · MB 229.51STAR EURO 5W-30
High-performance motorcycles5W-40JASO MA24T MegaTec 5W-40
Scooters10W-40JASO MB4T Plus MB 10W-40
Hydraulic systems / injectionISO VG 46DIN 51524 HLPAW Series Hydraulic Oil
FAQ

Oil selection FAQ

Can I use a thicker-than-specified oil (e.g. 5W-40 instead of 5W-30)?

A small step up can be fine for hot, heavy-load or high-mileage engines, but always stay within the owner's manual range. Too thick raises consumption and cold-start wear; DPF-equipped cars must keep their Low-SAPS spec.

Full synthetic vs synthetic vs mineral — what's the difference?

It comes down to base-oil grade: full synthetic has the best purity and high/low-temp stability and the longest drain interval; mineral is cheaper but degrades faster. Modern turbo and direct-injection engines should use full synthetic.

Can I use car oil in a motorcycle?

Not recommended. Most geared bikes use a wet clutch needing a JASO MA/MA2 oil; car oils often contain friction modifiers that can cause clutch slip. Use a motorcycle oil marked JASO MA2 (geared) or MB (scooter).

How often should I change the oil?

It depends on the oil grade, driving style and the manufacturer's advice. Full synthetic with normal use is often ~10,000 km or six months; shorten it for stop-go city, heavy load or heat. Follow your manual and the product TDS.

What approvals does ONEWAY hold?

ONEWAY holds Mercedes-Benz MB 229.3 and Porsche A40 approvals, plus ISO 9001:2015 and European EELQMS quality registration. See About.

Still not sure which oil to use?