Engine Oil Classification Chart(Complete Guide)

You might have noticed strings of letters and numbers on oil containers like 5W-30 or API SN. These aren’t just random, they signify important classifications that determine the oil’s viscosity, composition, and suitability for certain engines.

In this post, we will go over all engine oil classification systems. Let’s jump in.

Engine Oil Classification Chart

Here’s a detailed engine oil classification chart comparing global standards:

Standard	Category	Usage	Notable Examples
SAE	Viscosity Grades	All Vehicles	0W-20, 5W-30, 10W-40
API	Gasoline: SN, SP Diesel: CJ-4, CK-4	Cars, Trucks	API SN Plus, CK-4
ACEA	A/B, C, E	European Vehicles	A3/B4, C3, E9
ILSAC	GF-5, GF-6A/B	Fuel Efficiency	GF-6A
JASO	MA, MA2, MB	Motorcycles	JASO MA2

Understanding Engine Oil Classifications

Several organizations classify engine oils based on viscosity, chemical properties, and engine performance standards. These include:

SAE (Society of Automotive Engineers)
API (American Petroleum Institute)
ACEA (Association des Constructeurs Européens d’Automobiles)
ILSAC (International Lubricants Standardization and Approval Committee)
JASO (Japanese Automotive Standards Organization)

1. The SAE Classification System

SAE classifications focus on viscosity—the oil’s resistance to flow.

Monograde Oils: Used mainly in stable climate regions (e.g., SAE 30).
Multigrade Oils: Suitable for varying temperatures, indicated as XW-XX (e.g., 5W-30).

How to Read SAE Grades:

5W (Winter): Cold-start viscosity.
30: Viscosity at high temperatures.

2. API (American Petroleum Institute) Classification

The API categorizes oils for gasoline and diesel engines.

API Gasoline Classifications (Current):

SN: High-performance engines (since 2010)
SP: Latest for modern engines, turbocharged support, LSPI protection

API Diesel Classifications (Current):

CJ-4: Diesel engines with EGR, particulate filters
CK-4: Replaces CJ-4, enhanced oxidation stability

3. ACEA (European Automobile Manufacturers’ Association) Classification

ACEA oil standards are essential for European vehicles. They are classified into:

A/B: Gasoline and light-duty diesel engines
C: Catalyst-compatible, low SAPS oils for emission systems
E: Heavy-duty diesel engines

4. ILSAC (International Lubricants Standardization and Approval Committee)

ILSAC partners with API and focuses on fuel economy and emissions.

GF-5: Introduced in 2010, supports E85
GF-6A/B: For newer models, improved oxidation and LSPI protection

5. JASO (Japanese Automotive Standards Organization) Classification

Motorcycle engine oils use JASO standards:

MA: Wet clutch compatible
MA2: Higher friction, advanced performance
MB: Lower friction, used in scooters

How to Read Engine Oil Labels

A bottle labeled SAE 5W-30, API SP, ILSAC GF-6A means:

Works in cold and hot temperatures
Supports modern engines with turbochargers
Meets fuel economy standards

Choosing the Right Engine Oil for Your Vehicle

Always consult your owner’s manual for oil specs. Here’s a quick guide:

Cold climates: Choose 0W or 5W oils.
Hot climates: Opt for 10W or higher.
High mileage engines: Look for “High Mileage” labels.
Turbocharged engines: API SP or ILSAC GF-6A oils.

Impact of Incorrect Engine Oil Usage

Using the wrong oil can:

Reduce fuel efficiency
Increase engine wear
Cause overheating
Void manufacturer warranties

FAQs

What is SAE and API oil classification?

SAE (Society of Automotive Engineers) classification refers to the viscosity grade of engine oil. It uses a system like 5W-30 or 15W-40, which indicates how the oil flows at cold (W = winter) and hot temperatures. The lower the number before the W, the better it performs in cold starts.
API (American Petroleum Institute) classification identifies engine oil quality and performance standards. API classifies oils for:
- Gasoline engines: Indicated by “S” (e.g., SN, SP)
- Diesel engines: Indicated by “C” (e.g., CJ-4, CK-4)

What does 15W-40 mean in engine oil?

15W-40 is a multigrade oil. Here’s how to break it down:

15W: The oil’s viscosity rating at cold temperatures. The lower the number, the easier it flows in winter.
40: The oil’s viscosity rating at high operating temperatures. A higher number means it’s thicker at higher temperatures, providing more protection.

This oil is commonly used in diesel engines and heavy-duty vehicles.

What are the 3 grades of oil?

Engine oils are typically categorized into three main types or grades:

Mineral Oil (Conventional Oil) – Refined crude oil, is less expensive but requires frequent changes.
Synthetic Oil – Chemically engineered for superior performance and protection.
Semi-Synthetic (Blended) Oil – A mix of mineral and synthetic oils, offering a balance between cost and performance.

Which oil is thicker, 5W-30 or 10W-30?

10W-30 is thicker at cold temperatures than 5W-30. Here’s why:

Both oils have a high-temperature rating of 30, meaning they perform similarly when the engine is hot.
However, 5W flows better in cold conditions, offering better protection during cold starts.

So, 5W-30 is thinner in cold weather, while 10W-30 is slightly thicker.

What is the meaning of SN CF 5W-30?

This label includes both API classifications and SAE viscosity rating:

SN: API rating for gasoline engines, suitable for modern vehicles with turbochargers and emission systems.
CF: API rating for diesel engines (though it’s older and mostly replaced by newer standards like CK-4).
5W-30: SAE viscosity grade, suitable for cold climates and common in passenger cars.

It means this oil is a multi-purpose lubricant suitable for both gasoline and some diesel engines.

Which is better, SL or SN oil?

SN oil is newer and more advanced than SL oil. Here’s the difference:

SL: Introduced in 2001, designed for older gasoline engines.
SN: Introduced in 2010, with better protection against deposits, wear, and oil breakdown—especially for engines with turbochargers and exhaust after-treatment systems.

Unless your vehicle specifically calls for SL, SN is generally the better choice for modern engines.

Final word

Choosing the right oil doesn’t have to be overwhelming. By understanding the engine oil classification chart, you ensure your engine runs smoothly, efficiently, and for the long haul. Always refer to your manual, and when in doubt, go with oils that meet SAE, API, and ILSAC standards for the best results.