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Why Do I Need To Change My Oil?

What Happens to oil Making Me Needing to Change It?

Regardless of its quality, every motor oil eventually loses its potency and must be changed to ensure peak engine protection. Let’s take a look at what happens to motor oil over time and why you periodically need to change oil.

Losing the base

Base oils are the backbone of the finished lubricant that ends up in your engine. Over time, they lose effectiveness due to the following factors:

Oxidation

The interaction between oxygen molecules and motor oil molecules naturally leads to chemical breakdown.

Just as oxygen causes a cut apple to brown or exposed metal to rust, it breaks down base oils and reduces motor oil’s effectiveness.

Oxidation can lead to increased oil viscosity, which negatively affects energy efficiency. It also causes the formation of harmful deposits and sludge.

High heat

Today’s engines run hotter than ever before, with temperatures up to 235°F (113ºC), and even higher if towing or hauling.

The rate of oxidation for oil doubles for every 18°F (10°C) increase in temperature.

Moisture

Your vehicle is subjected to temperature swings, even when it is parked in the garage.

Those temperature swings cause condensation to form inside your engine, leading to water contamination.

Leaving a vehicle parked for extended periods or taking short trips that don’t allow the engine to fully warm up allow water to remain in the oil rather than evaporating and exiting through the tailpipe. Water can lead to formation of sludge…yet another reason why you must change oil.

Viscosity is a motor oil’s most important property. The lower the viscosity, the faster the oils flows, like water. Thicker oils flow more slowly, like honey.

Viscosity loss

A lubricant’s viscosity is its most important property.

Viscosity has a direct bearing on wear protection, and your engine is designed to operate best using a motor oil of a specific viscosity (e.g. 5W-30).

The intense pressure the oil bears as it’s squeezed between moving parts, like the piston ring/cylinder wall interface, can tear apart, or shear, its molecular structure, leading to viscosity loss.

Suddenly, the 5W-30 motor oil your engine was designed to use is now essentially a 5W-20 oil, and wear protection may be compromised. When this happens, it’s time to change your oil.

Fuel dilution

Fuel can wash past the piston rings and contaminate the motor oil, causing it to lose viscosity.

Frequent short trips that don’t allow the oil to reach normal operating temperature can be especially problematic because the fuel won’t volatilize and exit through the PCV system.

Excessive fuel dilution leads to sludge and varnish, requiring you to change oil more frequently.

Additives: Additives are added to base oils to reduce destructive processes and enhance beneficial properties.

For example, antioxidant additives help slow the rate of oxidation. Detergency additives help prevent deposits and sludge while cleaning pre-existing deposits. Formulators add anti-wear additives to some lubricants to form a sacrificial barrier on metal components and help prevent wear.

Since they’re sacrificial in nature, additive depletion is one of the primary reasons motor oil loses its effectiveness and must be changed. 

While AMSOIL synthetic motor oil gives you the convenience of fitting oil changes into your schedule, it remains vital to install fresh oil at the appropriate time.

ILSAC GF-6, API SP & dexos: Making Sense of New Oil Specs.

ILSAC GF-6, API SP & dexos: New Oil Specifications

As engine-operating conditions grow more severe, so do the demands placed on your motor oil. Hence the need for updated oil specifications, like ILSAC GF-6, API SP and GM dexos1 Gen 2.

New engine hardware such as turbochargers, direct injection and variable valve timing (VVT) place increased stress on your engine oil. This, in turn, has led to the introduction of more strict more oil specifications.

Here’s what we’re going to cover:

  • How strict fuel-economy standards increase engine stress
  • What is LSPI (low-speed pre-ignition)?
  • How motor oil helps prevent LSPI
  • ILSAC GF-6, API SP and GM dexos
  • Do AMSOIL synthetic motor oils meet GM dexos, ILSAC GF-6 and API SP specs?

 

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Improved fuel economy

Corporate Average Fuel Economy (CAFE) standards require a fleet-wide average of about 40 mpg by 2026 in the United States.

To meet these requirements the automotive industry has focused on smaller, more fuel-efficient engines. In fact, most new vehicles now feature gasoline direct-injection (GDI), a turbocharger or both (T-GDI).

Severe operating conditions

Smaller, more-efficient engines that make the power and torque of higher-displacement engines undergo more severe operating conditions that can lead to…

  • Severe engine knock, also called low-speed pre-ignition (LSPI)
  • Increased engine temperatures
  • Compromised fuel injectors
  • Increased wear and deposits if the oil isn’t up to snuff

The biggest motor-oil-related challenge on the horizon is LSPI, which can destroy pistons and connecting rods.

LSPI can cause cracked pistons and rods

LSPI is the spontaneous ignition of the fuel/air mixture before spark-triggered ignition.

It is another version of pre-ignition. Pre-ignition (engine knock) has been around since the beginning of internal combustion engines.

LSPI, however, occurs under low-speed, high-torque conditions, such as taking off from a stoplight in T-GDI engines.

This scenario can create conditions where the fuel/air ignites too early in the combustion cycle, throwing off the engine’s timing.

The expanding combustion charge collides with the piston as it’s moving up the cylinder, potentially destroying the pistons or connecting rods.

Oil can help prevent LSPI

Experts suggest the cause is due in part to oil/fuel droplets or deposits in the cylinder igniting randomly. The droplets and deposits contain enough heat to ignite the air/fuel mixture before spark-triggered ignition.

Oil formulation can play a role in reducing LSPI.

Certain motor oil ingredients can promote LSPI, while others can help reduce it. It’s tempting to think, “Well, dump a bunch of ingredients into your formulations that help reduce LSPI.” But some ingredients that help reduce LSPI have been limited over the years in motor oil formulations for other reasons.

It truly is a scientific balancing act confronting oil formulators. It’s no easy task to formulate motor oils that deliver excellent wear protection, resist the increased heat of turbocharged engines, prevent deposits, act as a hydraulic fluid and, now, combat LSPI.

The performance of the entire formulation – not just one or two ingredients – is what counts.

ILSAC GF-6, API SP and GM dexos

Next-generation motor oils need to pass an LSPI test to meet these new demands.

General Motors was first out of the gate and required oils to pass its own LSPI test. Its GM dexos1 Gen 2 specification took effect Aug. 31, 2017.

The latest American Petroleum Institute (API) specification, API SP, took effect in May 2020. As did ILSAC GF-6, the latest spec from the International Lubricants Standardization and Approval Committee. For the most part, it mirrors API specifications.

ILSAC has set a new precedent in the passenger-car motor oil market by splitting its specification into two parts. One of the main differences between the two specifications is compatibility.

See the chart below. Both versions focus on wear protection, prevention of LSPI and improved engine cleanliness. However, GF-6B features a more stringent fuel economy test.

Engine oils can easily be identified as ILSAC GF-6A or 6B by the API emblem on the front label of the packaging. A shield represents the GF-6B specification, while the traditional starburst indicates a GF-6A product.

Both ILSAC specifications meet the industry-standard API SP specification which is most commonly found in owners’ manuals.

Relax…for now

For now, you don’t have to worry too much about LSPI.

Your vehicle’s computer is programmed to avoid operating conditions that lead to LSPI. But, operating your engine under those conditions does promise fuel economy gains.

AMSOIL meets the latest specs

AMSOIL synthetic motor oils meet or exceed the latest industry standards, including ILSAC GF-6, API SP and GM dexos1 Gen 2.

You can safely use our synthetic motor oils in engines that call for those specifications.

In fact, AMSOIL achieved 100 percent protection against LSPI in the engine test required by GM’s dexos1 Gen 2 specification.*

*Based on independent testing of Signature Series 5W-30, XL 5W-30 and OE 5W-30 in the LSPI engine test as required for the GM dexos1® Gen 2 specification.