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Why Do I Need To Change My Oil?

Written by Charleen

What Happens to oil Making Me Needing to Change It?

Dan McClelland|

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.

Shop AMSOIL Synthetic Motor 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.

Shop AMSOIL XL 12,000 mile Synthetic Motor Oil
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How Engine Wear & Deposits Kill Horsepower

Written by Charleen

Common Engine Wear & Deposits Will Kill Horsepower

John Baker|

Most people equate engine wear and deposits with a sudden, catastrophic engine failure that leaves you stranded alongside the road. In reality, wear and deposits are more likely to erode engine power and efficiency over time. Here’s how it works and what you can do about it.

Engine compression = power

For your engine to produce maximum power, the combustion chamber must seal completely during the compression and combustion strokes. Wear and deposits can prevent the valves or piston rings from sealing, allowing pressurized gases to escape the combustion chamber and take potential engine power with them.

To illustrate, imagine using a hydraulic floor jack. Pumping the handle will raise the vehicle as long as the release valve is tightly seated and doesn’t leak. A poorly sealed release valve, however, allows pressure to escape, causing the vehicle to sink to the ground no matter how much you pump the jack handle.

The same principle applies inside your engine. If some of the pressure created during the compression and combustion strokes is lost due to valves and piston rings that don’t seal completely, the engine will create less power.

engine wear identified

Wear & deposits reduce compression

Over time, deposits or valve wear can prevent the valves from closing completely, interfering with a good seal. Wear can also interfere with proper valve operation, disrupting optimum fuel/air flow.

If the piston rings do not seal tightly against the cylinder wall, pressurized combustion gases can escape past the rings and enter the crankcase, taking potential power with it.

Worn or stuck piston rings produce the same effect. The rings are designed to move freely in their grooves and press tightly against the cylinder wall. They should form a seal that prevents fuel/air from escaping. Ring wear can interfere with formation of a tight seal. Likewise, deposit buildup can cause the rings to stick in their grooves, also preventing a good seal. As a result, some fuel/air escapes the combustion chamber during compression, reducing power. On the combustion stroke, pressurized gases can blow by the rings and travel down the cylinder wall and into the oil sump, taking potential power with them. This is what’s meant when someone says an engine has lost compression.

(Check out our 5 Ways to Boost Horsepower for Under $500)

AMSOIL Signature Series helps prevent the problem

AMSOIL Signature Series Synthetic Motor Oil provides…

  • 75 percent more engine protection against horsepower loss and wear*
  • 90% better protection against sludge **

Its outstanding performance helps prevent deposits and wear that rob engines of horsepower, helping preserve that like-new feeling you crave when driving.

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*Based on independent testing of AMSOIL Signature Series 0W-20, in ASTM D6891 as required by the API SN specification.

**Based on independent testing of AMSOIL Signature Series 5W-30 in the ASTM D6593 engine test for oil screen plugging as required by the API SN specification.

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