Before digging into changing oil, we must first understand the purpose of engine oil. The engine oil has four functions inside the internal combustion engine. These are the following functions of oil: cooling, lubrication, corrosion prevention and sealing.
Engine parts are made of metal. Typically, the crank shaft connecting rod and camshaft are parts exposed to oil. These are the major parts that provide fuel compression and power. Metal parts rubbing onto each will cause friction. As oil passes thru the metal parts, it creates a small film that serves as a barrier to avoid metal parts from shaving.
Metal expands as it engages with other metal object, hence the oil has the ability to cool the metal parts as it flows to the lubrication system and dissipating the heat. The oil film in between metal parts will also serve as a barrier in between the metal and contaminants outside such as dirt and oxygen. Rust will only occur when there is oxygen, a contaminant and an unprotected metal.
Is It by Period of Time or Milage?
The myth of changing oil every 3,000 km has been passed down for several years. According to AmericanScientific.com the reason behind this frequent oil change is to serve as a “cheap insurance” to avoid mechanical failure and a lucrative business for quick-lube service shops yet a harmful practice for the environment.
According to petroleum manufacturers, petroleum-based oil can max out at 5,000 kilometers before being considered at poor state. Meanwhile, a fully synthetic oil can withstand 10,000 to 15,000 kilometers at most. The frequency of changing oil at 3000km is considered to be an “overkill” practice.
The best thing would be milage but there’s a catch. The primary objective of oil is to provide lubrication and reduce the friction. Heat will degrade the oil’s quality, decreasing its surface tension. It is way better to change oil depending upon the milage. Milage dictates how far the vehicle have traveled, hence distance over time creates friction and wear in the oil.
But how about a car that barely travels? The answer would be every three months if we are talking about standard practice. Once an oil is opened up it is susceptible to contaminants, additives in the oil will degrade once it is opened up and poured into the system.
What oil is right for my car?
This question is dependent on your owner’s manual at least. The grade of the oil depends on what fuel system do you have. Diesel engines typically use 15w-40 engine oil grade and its gasoline counterpart run on 5w-30. I would like to emphasize that it is best to see your owner’s manual to get the right grade of oil.
Fully synthetic or not?
If you are going for a quality oil that lasts longer then fully synthetic oil will be better. Synthetic oil uses more refined base oil than a conventional oil. (mineral oil) Though conventional oil provides adequate lubrication; in any aspects it can’t out perform a fully synthetic oil. Non synthetic oil is less chemically stable, quicker to break down due to loss of protective qualities, oxidize and acidify quickly.
The major disadvantage of synthetic oil primarily I it’s price. It is more expensive than a conventional oil. Synthetic oils are also prone to additives precipitation during cold storage conditions.
Is Synthetic Oil Worth the Cost?
This is highly dependent on the oil you are purchasing as oils have different protection levels and formulation. A typical change oil would cost you $40 and a fully synthetic change oil is approximately at $70.
Fully synthetic could run 10,000 – 15,000 km before needing an oil change. It would cost at least $5.33 dollars a month to keep a car running on fully synthetic year-round.
Synthetic Oils on Its Roots.
There are different base oils (oils that holds the additives) for engine oils. PAO’s or Polyalphaolefins are more common base oil in today’s synthetic oils. This base oil has moderate price and a little negative
attributes. PAO is a group IV-based oil and has a similar characteristic of a mineral oil. Since PAO is made rather than extracted it is purer and has better chemical stability even though its chemical structure has a resemblance of a mineral oil.
Among the strengths of include improved oxidation and thermal stability, low volatility (potential to change rapidly), good heat dissipation, low pour point (temperature below which a liquid loses the ability to flow).
Another type of base oil in synthetic oil is called Ester. This oil belongs to group V of API (American Petroleum Institute). Among the common esters used for synthetic motor oil are diesters and polyol esters. Diester oil is commonly used to be an additive of PAO base stock oil. Ester oil have excellent pour point, high thermal efficiency but fells apart on its hydrolytic stability (ability of becoming semisolid or liquid when exposed to heat).
How Often Do I Change Oil?
The points mentioned above will give you insights on how often you should change oil. Driving conditions and lubrication type are among the aspects to consider when to change oil.
Driving conditions include temp of the environment, distance being travelled from time to time. The oil you pour on your car will also dictate when to change oil.