Survey by Qualaroo

Which oil to choose?

In order to answer this question, let us take a look at what are the different types of engine oils and how are the properties of one brand of oil different from another. One also has to keep in mind the conditions in which the engines are used when choosing its oil.

Synthetic vs. Conventional oil

Conventional / Mineral oils are based on petroleum oil which is refined from crude oil. They have chemically weak properties and deteriorate soon during normal engine operation.

Synthetic oils are refined and produced from stronger chemicals that can keep their properties for longer during normal and severe engine operation. Therefore, synthetic oil has long drain intervals compared to mineral oils.

Engine oil Grading

Engine oil has basically two grading systems; one is based on quality and performance called the API Grading and the second is based on the viscosity of the oil called SAE Grading.

1. Quality/Performance Grading (API GRADING)

2. Viscosity Grading (SAE GRADING)

API GRADING (Performance grading)

API (American Petroleum Institute) oil grading is based on the results and performance of many tests and trails of the engine oil.

For gasoline engine oil API Grading starts with the letter ‘ S ‘ (service category)

For diesel engine oil API Grading starts with the letter ‘ C ‘ .

Mentioned below is the latest API grading chart:

Gasoline Engine Oil

SM Current

It is for all automotive Gasoline engines currently in use. It was introduced in 2004. SM oils are designed to provide improved oxidation resistance and long drain interval.

SL Current

It is for 2004 and older automotive engines.

SJ Current

It is for 2001 and older automotive engines.

SH Obsolete

It is for 1996 and older automotive engine.

SG Obsolete

Not suitable for current engines.

SF Obsolete

Not suitable for current engines.

SE Obsolete

Not suitable for current engines.

SD Obsolete

Not suitable for current engines.

Diesel Engine oil

CJ-4 Current

It was introduced in 2006 for high-speed, four-Stroke diesel engines designed to meet highway exhaust emission standards of models 2007 and later. It is yet to be introduced in Pakistan.

CI-4 Current

It was introduced in 2002 for high-speed, four-stroke diesel engines designed to meet 2004 exhaust emission standards

CH-4 Current

Introduced in 1998.

CG-4 Obsolete

Introduced in 1995.

CF-4 Obsolete

Introduced in 1990.

CF-2 Obsolete

Introduced in 1994.

CF Obsolete

Introduced in 1994.

CE Obsolete

Not fit to use now a days.

SAE GRADING (Viscosity grading)

Viscosity grade indicates how thick or thin the oil is? Or in other words how viscose the oil is? Viscosity is defined as resistance to flow.

Viscosity grades are of two kinds; Mono-grades and Multi-grades engine oils.

Mono-grade oils are labeled as 0W, 5W, 10W, 15W, 20W, 20, 30, 40, and 50. Grades followed by ‘ W ‘ denote that the oil is tested in extreme cold weather conditions. ‘ W ‘ represents winter. Grades without ‘ W ‘ denote that the oils are tested at higher temperature ranges and are thicker in appearance.

Multi-grade oils have labels for both extreme cold and hot conditions. For example, the oil which has a label like 10W40 is called multi-grade engine oil.

Mentioned below is SAE J300 table for Viscosity Grading

SAE and ISO Viscosity Tables

SAE Viscosity Grades for Engine Oils SAE J300
SAE Oil Viscosity Grade Low Temperature º C Cranking Viscosity (mPa.s) Max (CCS) Low Temperature º C Pumping Viscosity(mPa.s) Max (MRV) Viscosity (mm ² /s) at 100 º C Min Viscosity (mm ² /s) at 100 º C Max High Shear Rate Viscosity (mPa.s) at 150 º C Min
0W 6200 @ -35 60000 @ -40 3.8 - -
5W 6600 @ -30 60000 @ -35 3.8 - -
10W 7000 @ -25 60000 @ -30 4.1 - -
15W 7000 @ -20 60000 @ -25 5.6 - -
20W 9500 @ -15 60000 @ -20 5.6 - -
25W 13000 @ -10 60000 @ -15 9.3 - -
20 - - 5.6 9.3 2.6
30 - - 9.3 12.5 2.9
40 - - 12.5 16.3 2.9 (0W – 10W)
40 - - 12.5 16.3 3.7 (15W – 25W)
50 - - 16.3 21.9 3.7
60 - - 21.9 26.1 3.7

Driving Conditions in Pakistan

Some types of car operations are more severe than others, placing greater demands on the motor oil and calling for more frequent oil changes. For this reason, car manufacturers give two recommendations for oil changes in their owner’s manuals.

Standard Service

Standard conditions are generally where a vehicle drives more than 15,000 km with out short distance, and congested & traffic jam condition where stop and go is very rapid. And there are few periods of long Idling (car keep started on stationary position).

Severe Service

This service is applicable where city traffic has no flow systematically, short trips drive where stop and go condition prevails, off road drive conditions, irregular loading conditions, to many long Idling etc.