Slick truths - All you might want to know about engine oil

(Published City Tribune - April 9 2007)

By Tushal Bhadang

Just like the human heart, your car has a heart - the engine. A modern car engine is an intricate network of narrow passages cast in metal and sealed by gaskets. The lifeline of an engine is the engine oil pumped through all the nooks and corners over all the internal parts.

No matter what the fuel used (diesel or petrol) metal rubbing against metal causes friction and hence wear and tear in an engine. Engine oil creates a thin film of lubrication between all the moving parts so that they can survive the intense heat, pressure and speed generated by the moving car.

Alesser known fact about engine oil is that it has cleansing properties (detergents), which are necessary to remove sludge (thick oily formation) from tappets, valve seats, crank shaft etc. and also to hold on to the nasty byproducts of combustion such as silica (silicon oxide) and acids. This cleaning action helps build a consistent layer of film on the moving parts and also keeps the engine cool. Engine oil is not a very interesting topic and hence motorists often ignore engine oil essentials. For starters, engine oil is available in various grades. Pick up a can of oil and you will come across jargon such as: “SAE/API SJ 20W40/50” on the label. SAE (Society of Automotive Engineers) and API (American Petroleum Institute) stand for the international grading authorities, “S” for petrol engine use, if “C” then for diesel engine use. The second letter indicates the quality of the oil, higher the better. An ‘SJ’ oil can be used for any engine requiring a lower grade like SB, SG, SH etc.

Now to explain the numbers - they denote the viscosity/thickness or resistance to flow. The lower the number, the thinner the oil and vice versa. So, ‘20’ denotes, that you can start the car safely with temperatures no lower than 20 deg. Fahrenheit. The Upper number ‘40/50’ is where the role of multigrade oil comes into the picture. For a country like Bahrain, where the ambient road temperature in the summers exceeds 50 deg. Fahrenheit, this grade is suitable. Oil, like any other liquid also tends to vaporise at high temperatures. Note that often after a high speed run, if you open the bonnet in peak summers ((if you dare to, that is!) and uncap the oil cap on the engine, you will notice light vapours rising. Excessive smoke means that your engine is actually heating up too much and vaporising the oil before it can do its job. Entering the garage now, is synthetic or semisynthetic oil, which, unlike pure mineral oil has additives and a modified molecular structure that helps it to ‘cling’ onto the metal parts. Hence it is better to use this kind of oil as compared to pure oil due to its better engine protection properties. It is also safe for the environment.

DON’T JUDGE OIL BY ITS COLOUR

Summer is soon approaching Bahrain and the chances of engine oil being vaporised also increase. Hence it is not only necessary to check the oil dipstick frequently (every

fortnight) but also part of good car maintenance. The procedure is clearly mentioned in your car’s owner manual. Garage mechanics make a quick buck by getting you to purchase new oil and filter from them, i.e. the mechanic will say that the oil has become dark black in colour and needs to be replaced. But your car doesn’t need an oil change unless you are getting key components like piston seals replaced. The dark colour of the oil is due to the carbon it has absorbed from combustion. Run a car for 10 minutes after a fresh oil change and it will change colour! A periodic oil change is necessary though, due to high temperatures in Bahrain and to maintain engine performance, a change

of oil and oil filter is recommended at 5,000 kms or 10,000 kms varying from car brand to brand. Buy a fresh pack of oil as far as possible and look out for improper storage of

packs before purchase as older oil may not be compatible with your modern car.

Use a proper grade that’s recommended for your car. You don’t need to use an expensive

grade of oil that goes into a E u r o p e a n luxury car for your small car. It would be in the best interest of your car and your comfort to invest in good quality oil. Peace of mind and better resale value are only some of the benefits. Don’t hesitate to ask your dealer for information about the oil they’re putting in your car, it’s your right to have a car that’s running smooth and clean.

OIL AND WATER DO NOT MIX

So do not pour your used oil onto the ground. Firstly, it’s worth noting that used engine oils are mildly carcinogenic and may cause cancer, specifically skin cancer. Don’t pour used oil into the sewage either. Take it to your nearest authorised car service station and they will know how to dispose it. Contact Hudson Quick Service in Bahrain to dispose off used oil.