Sir first of all check your owners manual for the recommended oil grade because i don't know what is recommended for Altis(5w-30 i presume)
How is Oil graded & its properties Information:
One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its viscosity. The viscosity of a liquid can be thought of as its "thickness" or a measure of its resistance to flow.The viscosity index is a measure of how much the oil's viscosity changes as temperature changes.The viscosity must be high enough to maintain a lubricating film, but low enough that the oil can flow around the engine parts under all conditions. A higher viscosity index indicates the viscosity changes less with temperature than a lower viscosity index.
Simply put, viscosity is the oil's resistance to flow or, for the layman, an oil's speed of flow as measured through a device known as a viscometer. The thicker (higher viscosity) of an oil, the slower it will flow. You will see oil viscosity measurement in lube articles stated in kinematic (kv) and absolute (cSt) terms. These are translated into the easier to understand SAE viscosity numbers you see on an oil bottle.
The numbers 0, 5, 10, 15 and 25 are suffixed with the letter W, designating their "winter" (not "weight") or cold-start viscosity, at lower temperature. That is for e.g 10w40 oil means its Viscosity when engine is cold,before ignition is 10 and 40 when it ts at optimum working temperature,which means its a multi grade oil that it changes its viscosity at different temperature ranges.
WHY MULTI GRADE?
Multigrade oil is oil whose viscosity properties have been changed artificially in order to slow down its rate of change of viscosity with temperature. Thus such oil tends to be thinner at low temperatures and thicker at high temperatures than monograde oil.
OK . . .What does a 5W-30 do that an SAE 30 won't?
When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Colder temperature. The numbers without the W are all tested at 210? F or 100? C which is considered an approximation of engine operating temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210? (100? C). The difference is when the viscosity is tested at a much colder temperature. For example, a 5W-30 motor oil performs like a SAE 5 motor oil would perform at the cold temperature specified, but still has the SAE 30 viscosity at 210? F (100? C) which is engine operating temperature. This allows the engine to get quick oil flow when it is started cold verses dry running until lubricant either warms up sufficiently or is finally forced through the engine oil system. The advantages of a low W viscosity number is obvious. The quicker the oil flows cold, the less dry running. Less dry running means much less engine wear.
BENEFITS OF A MULTIGRADE OIL
There are several benefits one may expect of multigrade oil.
When a vehicle is at rest for a few hours, all the engine oil comes down to the oil sump. Thereafter, when the vehicle is started, there is a certain time (probably only microseconds) before the oil reaches all the parts of the engine once again. Since the multigrade oil is thinner at low temperatures, it reaches all parts of the engine quicker than monograde oil and hence, reduces wear to that extent.
Generally, it has been observed that use of multigrade oils enables better fuel economy of 1.5% - 3%.
Multigrade oil offers better protection to the engine at high temperatures than monograde oil, since it is thicker than the monograde oil at temperatures above 100degreesC. This is so even if the multigrade oil is thinner than the monograde oil at temperatures below 100degreesC. This property of multigrades also reduces oil consumption.
API RATING
The American Petroleum Institute (API) sets minimum for performance standards for lubricants. Motor oil is used for the lubrication, cooling, and cleaning of internal combustion engines.The latest API service standard designation is SN for gasoline automobile and light-truck engines. The SN standard refers to a group of laboratory and engine tests, including the latest series for control of high-temperature deposits. Current API service categories include SN, SM, SL and SJ for gasoline engines. All previous service designations are obsolete
So begham ho kay apnay auto manual main recommended grade daal kar istamaal karain..As your ride is new i would recommend fully synthetic oil..Zic,Mobil,Caltex Havoline are all good oil..
THUS:
Change your Toyota Corolla's engine oil regularly, making sure to use an API certified SAE 5W30 engine oil if at all possible. If 5W30 isn't available, if you expect to operate your vehicle in extreme high temperatures or if your Corolla has extensive engine wear, 10W30 is a suitable substitute. You must not use 10W30 if temperatures are expected to fall below 0 degrees Fahrenheit.
5w vs 10w---5w wala oil will be quicker in flowing and thus lubricating the engine when engine starts when it is cold..10w wala will take little more time for the same measure of cold temperature in both cases for 0 degrees C.
Mujhay lagta hai 5w20 is not good at all,because the required viscosity for your car's engine at 100 Degrees centigrade is 30 not 20.Your car requires viscosity at the rate of 30 at high temperatures mgr yours is 20.(bhai jaan 30 ur 20 to Temperature say confuse na karain :D..These are all calculated observations regarding viscosity) .I suggest you get it changed IF THE OIL RECOMMENDED IN YOUR MANUAL IS 5W30. 5w40-10w40 is not bad bud i would stick with recommended manufacturers oil grade.
5w is for very cols starts..10w cant be used if starting temperature is below 0 Degrees..Aur 30-40 jub yeh increase hota jta hai means oils is more thick at high temperatures..Diff b/w 30 and 40 is kay 40 wala ziada thick ho ga at 100 Degrees centigrade than 30..Agar bhut ziada thick ho like 50 thus oil wont have time to flow with ease around the engine compartment but will be more thick.For 20 it will be more thin than required at high temperatures thus your current oil is not recommended.It is all about the car's requirement..Go with the manufacturer's recommended grade.
I know its an extensive explanation.But after carefully going through it you will understand the oil/grading mechanics like BAWZ!!
Any more questions feel free to ask
