Car Engine Oil Guide

All the oil information you need in one place

Selecting the correct oil for your vehicle can be a bit of a mine field. Some basic understanding of what the specifications are, and what the numbers printed in the can mean will be a help to selecting the correct oil.

 

Just about all modern vehicles use a multigrade oil, so what to does it all mean?

If you see an expression such as 10W-40, the oil is a multigrade. This simply means that the oil falls into 2 viscosity grades, in this case 10W & 40. This is made possible by the inclusion of a polymer, a component which slows down the rate of thinning as the oil warms up and slows down the rate of thickening as the oil cools down.

It was first developed some 50 years ago to avoid the routine of using a thinner oil in winter and a thicker oil in summer.

For a 10w-40 to attain the specification target a 10W ( W = winter) the oil must have a certain maximum viscosity at low temperature. The actual viscosity and the temperature vary with the viscosity grade but in all cases the lower the number, the thinner the oil, e.g. a 5W oil is thinner than a 10W oil at temperatures encountered in UK winter conditions. This is important because a thinner oil will circulate faster on cold start, affording better engine protection.

For a 10w-40 to attain the other specification target SAE 40 the oil must fall within certain limits at 100 degC. In this case the temperature target does not vary with the viscosity grade, if there is no "W", the measuring temperature is always 100degC. Again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC., which is typical of maximum bulk oil temperatures in an operating engine.

The engine makers are, of course, very well aware of this and specify oils according to engine design features, oil pump capacities, manufacturing tolerances, ambient temperature conditions etc. It is important to follow these guidelines, they are important and are an are stipulated for good reasons.

Now we know what the numbers are all about, lets have a look at what specifications there are, and what they mean. Many manufacturers will have their own specification for the oil required for a particular vehicle, these should be listed in the owners manual for the vehicle, BMW for example have the current BMW LL04 spec, for most BMW's post 2004, if the oil is approved to this spec it will be listed on the can.

In addition to manufacturer specifications there are also general specifications. The most popular are ACEA and API, again check the owners manual to find the correct spec for your car.

Here is a list of the specs.

API Specifications

API = American Petroleum Institute

S = Service - Petrol Engine Performance

C = Commercial - Diesel Engine Performance

PETROL

SG - Introduced 1989 has much more active dispersant to combat black sludge.

SH - Introduced 1993 has same engine tests as SG, but includes phosphorus limit 0.12%, together with control of foam, volatility and shear stability.

SJ - Introduced 1996 has the same engine tests as SG/SH, but phosphorus limit 0.10% together with variation on volatility limits

SL - Introduced 2001, all new engine tests reflective of modern engine designs meeting current emissions standards

SM Introduced November 2004, improved oxidation resistance, deposit protection and wear protection, also better low temperature performance over the life of the oil compared to previous categories.

SN – Introduced in October 2010 for 2011 and older vehicles, designed to provide improved high temperature deposit protection for pistons and turbochargers, more stringent sludge control, improved fuel economy, enhanced emission control system compatibility, seal compatibility, and protection of engines operating on ethanol-containing fuels up to E85.

DIESEL

CD - Introduced 1955, international standard for turbo diesel engine oils for many years, uses single cylinder test engine only

CE - Introduced 1984, improved control of oil consumption, oil thickening, piston deposits and wear, uses additional multi cylinder test engines

CF4 - Introduced 1990, further improvements in control of oil consumption and piston deposits, uses low emission test engine

CF - Introduced 1994, modernised version of CD, reverts to single cylinder low emission test engine. Intended for certain indirect injection engines

CF2 - Introduced 1994, defines effective control of cylinder deposits and ring face scuffing, intended for 2 stroke diesel engines

CG4 - Introduced 1994, development of CF4 giving improved control of piston deposits, wear, oxidation stability and soot entrainment. Uses low sulphur diesel fuel in engine tests

CH4 - Introduced 1998, development of CG4, giving further improvements in control of soot related wear and piston deposits, uses more comprehensive engine test program to include low and high sulphur fuelsSG - Introduced 1989 has much more active dispersant to combat black sludge.

CI4 Introduced 2002, developed to meet 2004 emission standards, may be used where EGR ( exhaust gas recirculation ) systems are fitted and with fuel containing up to 0.5 % sulphur. May be used where API CD, CE, CF4, CG4 and CH4 oils are specified.

CJ-4 – Introduced in 2010 exhaust emission standards. These oils are formulated for use in all applications with diesel fuels ranging in sulphur content up to 500 ppm (0.05% by weight). However, the use if these oils with greater than 15 ppm (0.0015% by weight) sulphur fuel may impact exhaust after treatment system durability where particulate filters and other advanced after treatment systems are used. Optimum protection is provided for control of catalyst poisoning, particulate filter blocking, engine wear, piston deposits, low and high temperature stability, soot handling properties, oxidative thickening, foaming, and viscosity loss due to shear.

ACEA Specifications

ACEA (European Automobile Manufacturers Association) have a system of rating oils, which you will find on the container of almost every oil on the market. These are the current specifications, previously oils were given separate petrol and diesel ratings, but from November 2004 onwards, those have been combined (A still refers to Petrol and B to Diesel engines).

A1/B1 Category for Fuel Economy engine oils with especially low High Temperature High Shear viscosity. HTHS of 2.6 to 3.5 mPas applies to XW-20, 2.9 to 3.5 mPas for all others. Corresponds to the old A1 and B1 specifications with some new engine tests.

A2/B2 Basic requirements.Will be replaced by the GLOBAL DLD-1 specification.

A3/B3 Category for high-performance and Fuel Economy engine oils. Exceeds ACEA A1/B1 with regard to Noack (evaporation losses), piston cleanliness and oxidation stability.Extended oil change intervals possible.

A3/B4 Same as A3/B3 but also for direct injection diesel engines.

A5/B5 Category for high-performance engine oils. For TDI engines with Fuel Economy Performance. In addition with lowered HTHS (2.9 to 3.5). Extended oil change intervals possible.

LOW SAPS Diesel Engines

An additional category appears in these specifications in which sulphate ash, phosphorous and sulphur content (SAPS) is limited.

C1 Largely based on the ACEA A5/B5. Strict limitation of SAPS content.Low HTHS viscosity of >2.9 mPas.

C2 Same as C1 but with somewhat higher SAPS content permissible (as with C3).

C3 Same as C2 except for HTHS > 3.5 and without Fuel Economy performance.

C4 Same SAPS content as C3, HTHS viscosity as C1.

As we said at the beginning, selecting the correct oil for your vehicle can be a bit of a mine field. This is where we can help, simply call us on 01209 202944 or email us at sales@opieoils.co.uk and our friendly team will be happy to help.

Popular Products
Just Added

Most Popular Products

Fuchs Titan Race Pro S 5W-40 Engine Oil

from only

£11.99

Start Shopping

Fuchs Titan Race Pro S 5w-40 Ester Synthetic Engine Oil, One of Our Most Popular Products At Opie Oils

Castrol EDGE TITANIUM 10W-60 FST Engine Oil

from only

£15.76

Start Shopping

Castrol Edge Titanium 10w-60 Fst, One of Our Most Popular Products At Opie Oils

Millers Oils CRX 75W-90 NT Full Synthetic Gear Oil

from only

£16.22

Start Shopping

Millers Oils CRX 75w-90 NT Competition Fully Synthetic Transmission / Gear Oil, One of Our Most Popular Products At Opie Oils

Motul RBF 600 Factory Line Brake Fluid

from only

£12.98

Start Shopping

Motul RBF 600 Factory Line Racing Brake Fluid, One of Our Most Popular Products At Opie Oils

view all

Just Added Products

view all

Review Opie Oils On Trust Pilot

Current Rating: Excellent

Review Opie

Latest Product Offers

Mobil 1 ESP 5w-30 Engine Oil
Mobil 1 ESP 5w-30 Engine Oil

On Offer

NOW: £36.95

Save: £15.03 Off List Price

Buy Now
Millers Oils NANODRIVE CFS 5w-40 NT+
Millers Oils NANODRIVE CFS 5w-40 NT+

New Product

NOW: £57.95

Save: £17.04 Off List Price

Buy Now
Shell Helix Ultra 5W-40
Shell Helix Ultra 5W-40

On Offer

NOW: £24.95

Save: £15.05 Off List Price

Buy Now
Fuchs Titan Race Pro S 10W-50 Engine Oil
Fuchs Titan Race Pro S 10W-50 Engine Oil

On Offer

NOW: £47.95

Save: £15.53 Off List Price

Buy Now
Castrol Edge Supercar 10w60 FST Titanium
Castrol Edge Supercar 10w60 FST Titanium

New Product

NOW: £44.95

Save: £11.82 Off RRP

Buy Now
Fuchs TITAN SYN MC 10w-40 Engine Oil
Fuchs TITAN SYN MC 10w-40 Engine Oil

On Offer

NOW: £17.95

Save: £2.26 Off List Price

Buy Now
Free Expert Advice!

Hundreds of customers contact us on a daily basis to discuss their oil needs and applications prior to purchase. We don’t just sell oils; we know oils and would encourage anyone to contact us to discuss any questions they may have. If you would like an expert recommendation then simply complete our oil recommendation form and one of our resident experts will aim to get your bespoke oil recommendation to you within 24 hours.

Get Expert Advice
What Fits My Car?

Enter basic information about your vehicle and our product lookup will provide you with the correct specification and amount of engine oil together with an OEM Spec & approved oil filter for a full service. Alternatively you can select just the engine oil or a 1 litre top up kit. In the near future this service will be improved so you will be able to source all fluids and essential service parts for your vehicle.

Use Our Product Finder
Everyday Driver

Within the automotive industry there is a lot of myths and confusion about certain elements of lubrication, fluids and oil. In order to cover, in detail, some of the most common things that are discussed by Opie Oils Technical Experts we have produced a collection of Technical PDF Downloads, some that Opie have produced and some sourced by experts within the trade that have given consent for us to share.

Read a Guide To Oils

Telephone Number: 01209 202949 Email: sales@opieoils.co.uk

Opie Oils, The Fuel Depot, Cardrew Industrial Estate, Redruth, Cornwall, TR15 1SS

© Opie Oils Limited Reg No. 02993088

Secured By Sage Pay Pay Through Our Pay Pal Portal Pay With Visa Pay With Mastercard Pay With Visa Electron Pay With Maestro Pay With Discover Pay With Delta Pay With American Express