Pour point depressants can reduce the viscosity at low temperatures, and viscosity index improvers can thicken the oil at high temperatures. The resulting stew of chemicals yields a 5W motor oil, common within the industry. Over time, however, the chemical additives used in the conventional oil to alter its properties begin to break-down, vaporize, or get used up. As contaminants begin to work their way into the oil, the overall trend over a long duration is that the oil thickens across the entire spectrum.
An old and used conventional 5W oil behave very differently than a brand new 5W Synthetic oils work quite differently. From the start, the chemical structure is designed to match a specific multi-grade oil. That means even without additives, you could have a 5W motor oil, and then certain additives like rust-inhibitors or dispersants will be added to further improve the usefulness of the oil. Since then, most major oil manufacturers have jumped in with their own synthetics.
Today, consumers have their choice of conventional, synthetic-blend, and synthetic motor oils, although not all oils are the same. Synthetic oil is made in the lab, thus each manufacturer takes different approaches. No manufacturer is about to share proprietary information about the process, but we can deduce certain facts about development without sounding like a chemistry professor in the process.
Full synthetic, or percent synthetic oils, are usually extracted from crude oil or a byproduct of the same. In the case of Pennzoil, they have figured out how extract synthetic oil from natural gas. Just like conventional oil, synthetics are refined. From there, the differences become apparent as synthetic motor oil is distilled and purified, before it is reduced to its basic molecules.
These harmful conditions include combustion byproducts, fuel contamination, water contamination, metal particles, acids, pro-oxidants and extreme heat e.
Exposure to these conditions commonly occur in engines. Oil degradation can cause sludge, varnish or deposits, corrosion, viscosity change and impaired engine performance. Synthetics have a naturally higher viscosity index. This means the viscosity changes less more stable as temperature changes during normal engine startup and operating conditions. Viscosity is an important property of lubricants that produces the film thickness or clearance between metal surfaces that slide or rotate against each other.
Without this film thickness, excessive friction and wear would occur. At extremely low temperatures, it is more possible for mineral oils compared to synthetics to become so thick high viscosity that the oil is unpumpable or is unable to circulate effectively within the engine. Lack of oil circulation can cause lubricant starvation conditions and engine failure. Synthetic engine oils are generally less volatile than mineral oils.
This means there is less loss of the oil to the engine's exhaust stream causing atmospheric pollution. This could also mean less need for makeup oil between oil changes. Possibly the biggest advantage and the reason synthetic oil is so popular, is that it has a longer lifespan than conventional oil.
The recommended change interval for synthetic oil is around every 5, to 7, miles, with some brands touting a much longer interval 15, to 25, The biggest reason for the longer oil change interval is described in the first bullet above.
Regardless of the kind of oil you use, it is still recommended to change your oil at regular intervals recommended by your manufacturer.
A few disadvantages of synthetic oil to be aware of include: Probably the most glaring downside of synthetic oil is the cost. The price of synthetic oil is around two to four times the price of conventional oil.
Synthetics may be more prone to additives precipitation during cold storage conditions. This stratifies certain additives which can potentially lead to their complete separation from the oil. Multi-grade motor oils using synthetics may exhibit slightly less fuel economy at highway speeds compared to mineral oil. This is due to the fact that mineral oils require more viscosity index improvers an additive than synthetics.
This additive contributes to reduced viscosity friction by a mechanism known as shear-induced temporary viscosity thinning. Synthetic Engine Oils: Digging Deeper Synthetic oil used in motor vehicles is refined from base oils or base stock oils.
PAOs are the most common type of synthetic base oils used today thanks to their moderate price and little negative attributes. PAOs are Group IV base oils and are similar to mineral oil in their chemical makeup but the fact that it's built rather than extracted makes it purer. The benefits of PAOs 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 and it's free of waxy molecules.
Esters- a Group V base oil made from ester oils is created from the reaction of acids and alcohols with water molecules splitting off. The most common esters used for synthetic motor oil are diesters and polyol esters. Diesters are commonly used as an additive with PAO base stock oil. Esters have high thermal stability and excellent low pour point characteristics but poor hydrolytic stability the resistance of a cured polymer material to going back to a semisolid or liquid form when exposed to high temperatures and humidity.
May not bear API service classification marks. Additive stability in cold temperatures for extended periods of time may be a problem. All engines generate contaminants such as soot, carbon, and sulfuric and nitric acid.
These contaminants are inevitable byproducts of the combustion process, and all of them end up in your motor oil, to varying degrees. To put it simply, a cleaner engine is better protected, has a higher quality performance, and works more efficiently than a dirty one. Many people wonder about the benefits that come from using synthetic motor oil made from natural gas, especially since they notice the price tag is slightly higher than conventional motor oil.
It all comes down to science and innovation. The chemically engineered molecules in synthetic base oil have more uniform properties while the molecules found in conventional base oil differ in shape and levels of impurity.
Pennzoil Synthetic motor oil, takes things to the next level of performance because they use base oil made from natural gas, which is purer than base oil made from crude oil.
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