Conventional oil, often referred to as mineral oil, is refined directly from crude petroleum. It undergoes basic purification and contains natural hydrocarbons along with some additives to enhance its lubricating properties.
Key Characteristics:
In hot climates like Phoenix, where ambient temperatures can rise well above 100°F, the performance of conventional oil can suffer. Its molecular structure is not as stable, making it more susceptible to oxidation and thermal breakdown—two issues that can accelerate engine wear.
Synthetic oil is man-made, developed through complex chemical engineering that tailors molecules for optimal lubrication, stability, and longevity. These oils are designed to handle extreme temperatures, heavy loads, and extended intervals between changes.
Key Characteristics:
For heavy-duty diesel engines operating in Phoenix’s harsh climate or hauling under full load across long distances, synthetic oil offers unmatched protection. It resists sludge formation and oxidation far better than its conventional counterpart.
Synthetic oil holds its viscosity across a wide range of temperatures. It remains fluid during cold starts and maintains thickness under heat. Conversely, conventional oil can become too thick in cold weather and too thin in high heat, jeopardizing protection.
Oxidation leads to sludge and varnish buildup inside the engine.
Because synthetic oil maintains a stronger film strength at high pressures and temperatures, it better protects critical components such as camshafts, lifters, and turbochargers. This is vital in engines under constant strain from heavy loads or long-distance hauling.
Most fleet operators are familiar with the classic 5,000- to 7,500-mile oil change interval using conventional oil. However, synthetic oil can extend this interval up to 15,000 miles or beyond—depending on the manufacturer, engine condition, and duty cycle.
While synthetic oils cost more upfront, the reduced maintenance frequency often makes up for it. In a commercial setting where downtime means lost revenue, fewer oil changes translate into lower labor costs and increased vehicle uptime.
Another factor to consider is fuel economy. Although modest, synthetic oil offers less internal drag thanks to its molecular consistency, allowing diesel engines to run slightly more efficiently. Over thousands of miles, this can result in tangible fuel savings for large fleets.
Furthermore, synthetic oils are more environmentally friendly when used properly. Their extended life means fewer oil changes, less waste oil, and reduced environmental impact.
While synthetic oil is often the better performer, conventional oil still has its place—especially in older engines not originally designed for synthetics, or in low-mileage, low-load applications.
Here’s a quick breakdown:
A common question in the field is whether you can switch between the two types. The answer is yes—modern engines can typically handle the transition from conventional to synthetic without issue. However, a high-mileage engine with existing sludge buildup may need gradual flushing or a high-mileage synthetic formula to prevent dislodged debris from causing harm.
Although synthetic oil can cost 2 to 3 times more per quart than conventional oil, the long-term benefits usually outweigh the price:
Fleet managers often find that synthetic oil pays for itself, especially when extended drain intervals are factored into the total cost of ownership.
When comparing synthetic vs. conventional oil in trucks, the answer lies in your specific use case. For trucks operating in intense heat, towing substantial loads, or traveling long distances, synthetic oil is often the best investment. While conventional oil can serve adequately in less demanding scenarios, the superior protection, performance, and efficiency of synthetic formulations make them the top choice for most heavy-duty applications.
Ready to upgrade your truck’s oil? Get in touch with our team at Onsite Truck & Equipment Repair for expert oil services in Phoenix, AZ.
