Why You Should Never Exceed 7,000–9,000 km Between Oil Changes

Protecting Your Engine's Lifespan, Performance, and Efficiency

When it comes to maintaining the performance and longevity of your vehicle, regular oil changes are one of the most crucial services—and yet, they are often overlooked or delayed. At Oakville Import Auto Centre, we’re often asked, “Is it really that bad to go a few thousand kilometres over my oil change interval?” The short answer: yes, it can be. And here’s why.

1. What Engine Oil Really Does

Engine oil isn’t just a fluid that keeps things moving. It plays a critical role in protecting and maintaining the health of your engine. High-quality motor oil:

• Lubricates moving engine components

• Reduces friction and wear

• Absorbs and dissipates heat

• Cleans internal surfaces by carrying away dirt and debris

• Prevents corrosion and sludge buildup

But oil isn’t invincible. Over time, it breaks down—especially when exposed to extreme heat, moisture, contaminants, and combustion byproducts.

2. The 7,000–9,000 km Rule: What Happens Beyond That?

Modern synthetic oils can last longer than traditional oils, but even high-end oil has a limit. Once you go beyond 7,000–9,000 km, you start putting your engine at serious risk.

Here’s why:

a. Oil Contamination from Unburnt Fuel

During normal engine operation, tiny amounts of fuel bypass the piston rings and enter the crankcase—a phenomenon called blow-by. This unburnt fuel mixes with the engine oil in the sump, diluting it and reducing its lubricating power.

Fuel-contaminated oil becomes thinner and loses its protective film strength, meaning it can no longer effectively separate metal parts. The result? Increased friction, wear, and a higher risk of overheating.

b. Breakdown of Oil Molecules

Oil is made up of complex molecules designed to maintain viscosity and protective qualities at high temperatures. However, prolonged exposure to engine heat and stress causes these molecules to degrade. As the molecular structure breaks down, the oil becomes:

• Less effective at reducing friction

• Poor at handling heat

• Sludgy or varnish-like in texture

This chemical degradation accelerates past the 7,000 km mark, especially in stop-and-go driving or under load, like towing or long idling times—conditions common in Oakville traffic.

c. Sludge Formation and Deposits

As oil ages and collects more contaminants, sludge starts to form. Sludge is a thick, sticky residue that clogs oil passages and restricts oil flow. If not addressed, sludge can lead to:

• Poor engine performance

• Decreased fuel efficiency

• Costly engine repairs

• Complete engine failure in extreme cases

d. Damage to Critical Engine Components

Vital engine parts such as camshafts, crankshafts, bearings, and turbochargers depend on a constant supply of clean, high-quality oil. Once oil becomes compromised, these parts can suffer premature wear or catastrophic damage.

Even high-end European or Japanese imports—known for precision engineering—can’t protect themselves against degraded oil.

3. Modern Cars Still Need Regular Oil Changes

There’s a common misconception that newer vehicles can go 15,000 km or more between oil changes, especially if they’re using synthetic oil. While some manufacturers do promote extended intervals, those recommendations assume ideal driving conditions—no extreme temperatures, no short trips, and no traffic congestion.

Here in Oakville, with changing seasons, busy streets, and varied driving habits, conditions are far from ideal.

4. Warning Signs You're Overdue for an Oil Change

If you’ve gone past your recommended interval, your vehicle may already be trying to tell you. Watch for:

• Engine noise or knocking

• Burning oil smell

• Dark or gritty oil on the dipstick

• Decreased fuel economy

• Check engine or oil warning light

Ignoring these signs could lead to engine damage and expensive repairs down the line.

5. Protect Your Investment—Schedule Regular Oil Changes

At Oakville Import Auto Centre, we specialize in maintenance for luxury and import vehicles, from BMW and Audi to Lexus and Acura. We only use high-quality synthetic oils that meet or exceed OEM specifications, and we track your service intervals to make sure you’re always protected.

Regular oil changes every 7,000 to 9,000 km not only help extend the life of your engine, but also:

• Maximize fuel efficiency

• Improve engine performance

• Maintain your manufacturer’s warranty

• Increase resale value

Final Thoughts: Oil is Cheap. Engines Aren’t.

It’s a simple truth: a timely oil change can save you thousands of dollars in engine repairs. It’s not just about mileage—it’s about protecting your engine from the inside out. Don’t wait until it’s too late.

Need an oil change in Oakville? Book your service with Oakville Import Auto Centre today. Your car—and your wallet—will thank you.