Motor Oil Functions | 6 Surprising Things Your Oil Does

By Vyscocity Inc. | July 15, 2025 |

AMSOIL OE 0W-16 synthetic motor oil next to a dirty filter, highlighting its cleaning function

Cleaner internals start with better oil. Powered by Vyscocity.

Motor Oil Functions | 6 Surprising Things Your Oil Does (Besides Lubricate)

Most people think motor oil's only job is to make things slippery. But the truth is, modern motor oil functions go far beyond reducing friction — especially when you're using a premium synthetic like AMSOIL.

In fact, engine oil is often the unsung hero of engine longevity and performance. If you think it just “keeps things smooth,” you're missing half the story. Below, we'll break down six lesser-known but critically important functions of engine oil — and how the right product can save you from sludge, scoring, and serious repair bills.

1. Transfers Energy – One of the Most Underrated Motor Oil Functions

While it may sound odd, many lubricants double as power transfer mediums. In systems like power steering, automatic transmissions, and even variable valve timing, the engine oil isn't just protecting parts — it's actively doing work.

✅ In hydraulics, the fluid transfers force through pressure
✅ In transmissions, oil transmits torque through valves and clutches
✅ In cam phasers, engine oil controls timing adjustments

Why it matters: If your oil shears down or loses viscosity, it can't transfer energy effectively. That leads to rough shifts, poor timing control, or even failure in hydraulic lifters.

🛠️ AMSOIL Advantage: Fluids like Signature Series ATF and 100% Synthetic Motor Oil are engineered with shear-stable base stocks that maintain viscosity under stress.

2. Cleans Internals – A Vital Function of Engine Oil

You wouldn't run your car with a clogged air filter — so why settle for dirty oil?

Modern oils are loaded with detergents and dispersants that clean your engine as you drive. These additives:

Trap carbon, soot, and varnish
Prevent sludge buildup
Keep oil passages, piston rings, and lifters free of debris

Low-quality or worn-out oil allows dirt and grime to accumulate, reducing flow, efficiency, and protection.

AMSOIL Advantage: Signature Series Synthetic resists sludge formation 90% better than conventional oils in industry testing. Your engine stays cleaner longer — which means fewer breakdowns and better fuel economy.

3. Cools Under Pressure – What Motor Oil Does Beyond Lubrication

Engines and gearboxes generate immense heat. While your radiator gets most of the attention, motor oil quietly carries away heat from internal hot spots, including:

Pistons and connecting rods
Bearings and crank journals
Valvetrain components
Transmission gears

This is even more critical in air-cooled engines, turbochargers, and racing applications — where localized heat spikes can exceed 300°F.

AMSOIL Advantage: Synthetic base oils like those in AMSOIL V-Twin or Signature Series have naturally higher heat resistance and better oxidation control. They won't burn off or break down when the going gets hot.

Diagram showing the main motor oil functions: lubricates, cools, cleans, seals, protects, and reduces wear inside an engine

Motor oil functions go beyond lubrication — it cleans, cools, seals, and protects your engine from the inside out.

4. Seals Out Contaminants – A Forgotten Motor Oil Function

Yes — engine oil actually seals things.

A thin film of oil between piston rings and cylinder walls helps maintain compression and block contaminants like:

Exhaust byproducts
Fuel vapors
Dust and dirt
Moisture from the air

If your oil is too thin or worn out, you'll experience blow-by, power loss, or cylinder wall scoring.

AMSOIL Advantage: Synthetic molecules are uniform and polar, forming a strong and stable seal. This is especially helpful in high-mileage or turbocharged engines where ring seal integrity is critical.

5. Cushions and Dampens Shock

Did you know gear oil acts as a cushion? It absorbs the shock between metal parts slamming together — something no coolant or sensor can fix.

Examples of this function include:

Motor oil cushioning rod bearings from crankshaft hammering
Fork oils damping impact in motorcycles and ATVs
Gear oil absorbing drivetrain shock under load

AMSOIL Advantage: Severe Gear® 75W-90 and other AMSOIL gear oils are engineered for heavy shock-loading — perfect for towing, rock crawling, or racing. They reduce clunk, chatter, and premature gear wear.

6. Prevents Rust and Corrosion – Even When Your Engine Isn't Running

One of the most important motor oil functions happens when your vehicle is just sitting in the garage.

Rust inhibitors and anti-corrosion additives in oil coat metal surfaces, protecting them from:

Water intrusion
Condensation from short trips
Acids formed during combustion
Salt or humidity from storage conditions

Boats, motorcycles, hot rods, and snowblowers are especially vulnerable to moisture-related corrosion during off-season storage.

AMSOIL Advantage: Products like AMSOIL Z-ROD® and Marine Synthetic Motor Oil include high TBN and specialty additives that protect stored engines long after the key is off.

How to Tell if Your Oil is Failing at These Functions

If your oil is no longer doing its job, your engine will tell you — often with expensive consequences:

Sludge buildup
Increased engine noise
Low oil pressure or lifter tick
Blown seals or smoky exhaust
Delayed shifting or overheating
Rust on dipstick or filler cap

Most of these issues trace back to oil that's lost its cleaning, sealing, cooling, or pressure-handling abilities.

So… What's the Takeaway?

Most drivers think their oil just needs to be “slick.” But true protection means your oil must:

✅ Transfer energy

✅ Clean internal parts

✅ Carry heat

✅ Seal compression

✅ Cushion metal contact

✅ Fight corrosion

If your oil fails at any of these engine oil functions, you're headed for trouble. Choosing the right lubricant makes the difference between a healthy engine and a costly failure.

Why AMSOIL?

Because AMSOIL isn't designed to just meet industry standards — it's built to exceed them.

With lab-verified wear protection, ultra-clean synthetic base oils, and over 50 years of innovation, AMSOIL products handle every critical motor oil function better than conventional oils.

Backed by tests. Proven in the real world. Trusted by riders, racers, fleets, and gearheads.