Engine Oil and its viscosity
lubrication of the engine the oil should possess some functional properties
of which viscosity of oil is one of the most important properties, as it
brings out the oils capacity to lubricate. Viscosity is the measure of
oils resistance to flow. An oils viscosity is identified by its
SAEs (Society for Automotive Engineers) number. The thinner and
oil, lower its number, e.g. SAE 10 W. The numerical relates to viscosity at
particular temperature and the alphabet W, indicates the oils
suitability for colder temperature. With the viscosity index improver, the
viscosity increses at higher temperature and at lower temperature it does
not increase significantly, thus achieving optimum viscosity at lower and
higher temperature. Such oils are called multigrade oils, for instance 20
W40 shows thinness at low temperature and thickness at higher
temperature. However, there are other
service classification of oil apart from viscosity, developed by API-
American Petroleum Institute, which indicates service characteristics. It is
graded on a scale from SA (the lowest) to SJ (the highest) for gasoline
engines, it is graded on a scale from CA to CG. Both the recommendations for
viscosity and service classification can be found on label of the oil
As we are extremely affected by the prices, quality and other vagaries of
the fuel available, we tend to forget that caring to use correct type of oil
is perhaps more important than the fuel. Just like any other subject on
cars, the first and the best guide for vehicle owners is to follow very
carefully maintenance o instruction manual provided by the manufacturers. If
one has questions or is unsure about which product to use, contact the
manufacturer of the preferred brand of oil. They are specialists with
extensive knowledge of petroleum chemicals to remove or ignorance of good.
Of course there are always proficient hands to help you at your own dealers
The quality of oil is determined by SAE
viscosity grades and by API service classifications. It should then be
matched with the recommendation in the service manual and with the label on
the oil container having SAE and API ratings. One can always refer to the
specification sheet that gives detail on product performance. This enables
one to understand why certain brands exceed by large margin the safety and
performance level set by SAE and API standards by a higher quality of oil
and viscosity range- something which is not necessary for every car- but
yes, for high performance and luxury cars.
Oils should always be changed at the
intervals recommended by the maintenance manual. These days the drain life
of an engine oil is anywhere between 5000 to 15000 kms (or even more) or six
months to one year, whichever is first. At times, due to unusual
circumstances, there may be shorter periods to change the oil especially if
one drives short distances and a lot of switching on and off of the engine
is involved. The condition of the engine oil can also be felt by the
slickness of the oil. But your fingers and thumb will need lot of experience
to know that. Your trusted service man can always help you.
It always safe to have the level of oil indicating on the dipstick between
MIN and MAX marks. One should check the oil level at least once every two
weeks or after every 1000 kms, and specially before a long journey. It is
dangerous for the engine to run with low or no engine oil. And remember, the
colour of the oil has nothing to do with its ratings or performance, it has
nearly cosmetic value.
Change of filters is normally recommended with
every oil change considering the impurities of fuel and dusty condition of
It is a good habit to keep engine running at
idle for few minutes after it is started. One should not rev the engine.
This allows the oil to flows all over the moving parts before any load is
placed on the engine. Remember, the maximum wear and tear of the engine
takes place when it is started for the first time of the day.
Always purchase replacement oils from trusted and established source. And
make sure the oil and the filter is changed in your presence, Recheck the
drain pug to know if it is plugged properly.
The care the lubricant manufacturers take in their packaging and sealing
indicates the seriousness of the matter.
- Use only recommended engine oil. It
should be in the owners manual and if you are unsure call up the
manufacturer or the dealer.
- Change the engine oil every six months
or five thousand kms, whichever is earlier.
- Make a note of your last oil change. At
the time oil change make sure you use the recommended lubricants only.
Check the packaging of the oil to make sure it is not spurious.
- Always buy from recognized dealers and
- Change oil filter at the time of an oil
- Never drive your vehicle if the engine
oil level is low or it does not have engine oil.
- Most cars have an indicator for engine
oil on the dashboard instrumentation plaster. If it indicates low oil do
not drive the car till you refresh the engine oil.