When it comes to changing engine oil, many of us wonder if using long-life oil and extending the oil change interval is safe. In theory, long oil change intervals sound great—fewer trips to the service station, less expense, and more convenience.

But is it really that simple? Let's explore this in detail.

Why Oil Quality Matters

In our country, engine oil quality is mainly classified based on API (American Petroleum Institute) standards. These standards evaluate oil based on factors like low-temperature fluidity, high-temperature stability, oxidation resistance, anti-wear properties, corrosion protection, and compatibility with engine parts. The higher the API rating, the better the oil quality.

For example, Shell's premium engine oils focus on three key aspects: resisting acid corrosion, preventing deposit buildup, and minimizing wear and tear. These qualities ensure that the engine remains clean, protected, and performs optimally even under harsh conditions.

Impact of Diesel Quality on Oil Change

Diesel quality plays a big role in determining the oil change interval. Diesel fuel contains sulfur, which generates acidic byproducts during combustion. These acids corrode engine parts and reduce the effectiveness of oil additives. As diesel quality improves (from Euro 1 with ≤2000 ppm sulfur to Euro 6 with ≤10 ppm sulfur), the amount of acid produced decreases, allowing for longer oil change intervals.

However, this doesn't mean we can extend the oil change interval endlessly. Even if we use high-quality diesel and long-life oil, factors like fuel consumption, engine workload, and driving conditions impact how often we need to change the oil.

Can Fuel Consumption Affect Oil Change Intervals?

Absolutely! Fuel consumption affects the temperature and condition of the engine. For instance, if a truck burns 35 liters per 100 km, it generates the optimal heat to expand piston rings, preventing excessive exhaust gas from entering the oil sump. Under these conditions, a 100,000 km oil change interval might be feasible.

But if the same truck burns only 28 liters per 100 km, the engine runs cooler, causing more exhaust gas to contaminate the oil. This means the oil change interval should be shortened to around 75,000 to 90,000 km. So, lower fuel consumption doesn't necessarily mean longer oil change intervals—it can actually mean the opposite!

How Does Oil Handle Deposits and Wear?

Oil plays a critical role in keeping the engine clean. During combustion, high temperatures generate carbon deposits that accumulate on the exhaust valves, piston rings, and turbochargers. These carbon deposits also find their way into the oil, forming tiny particles called soot.

Good quality oil contains dispersant additives that prevent these particles from clumping together, preventing wear and tear. If the oil quality is poor or used for too long, these deposits can thicken the oil, increasing fuel consumption and damaging engine components.

Anti-Wear Protection: Why It's Essential

One of the key functions of engine oil is to protect engine parts from wear. Modern engines operate under higher pressures and temperatures, which makes it critical for the oil to maintain a strong lubricating film. Anti-wear additives such as phosphorus, zinc, and molybdenum are added to the oil to reduce friction and protect components.

However, as environmental regulations tighten, the levels of these additives are being reduced to minimize harmful emissions. This shift makes it even more important to choose high-quality oil that balances wear protection and environmental standards.

Choosing the Right Oil Grade

API oil quality standards are backward compatible, meaning a higher-grade oil can replace a lower-grade one. However, upgrading oil quality does not mean we can extend the oil change interval or use lower-grade oil to change it early.

For long oil change intervals, it's best to use synthetic or semi-synthetic oil with high alkaline reserves and superior additives. These oils provide better protection, maintain stability, and extend engine life.

Why Stick to Manufacturer Recommendations?

For trucks with long oil change intervals, it's best to follow the manufacturer's recommendations and get the oil and filters changed at authorized service centers. Different oils may have the same API rating but vastly different alkaline reserves, which are key for extending oil life.

Engines equipped with Exhaust Gas Recirculation (EGR) or Diesel Particulate Filters (DPF) require high-quality oil that can handle increased soot and minimize DPF clogging. Using oil that meets or exceeds API CJ standards ensures better protection and reduces maintenance issues.

Final Verdict: Is Long Oil Change Safe?

Yes, long oil change intervals can be safe—but only if the right conditions are met. High-quality synthetic oil, clean diesel, and consistent fuel consumption are essential for maintaining engine health. However, pushing the limits without understanding these factors can lead to costly repairs.

Lykkers, always follow the manufacturer's guidelines, use high-quality oil, and don't assume that longer oil change intervals automatically mean better maintenance. What's your take on long oil change intervals? Have you ever experienced engine issues due to extended oil change periods? Share your thoughts with us!