Synthetic vs. Conventional Oil

The first cars used mineral oil (commonly referred to as conventional oil) because it is naturally occurring. However, the science of lubrication has come a long way in the past century. That added technology and protection does come with a higher price. So it’s natural to wonder if it’s worth it.

The key difference between today’s synthetic oils and mineral oils (other than price) is the refinement process. Synthetic oil involves a more intensive refining process that results in uniform molecule sizes. This helps synthetic oils to withstand a wide range of temperatures and perform consistently over long periods of time. It will flow better in low temperatures and protect better in extreme heat.

Synthetic oil has a higher viscosity index than conventional oil, meaning it provides thicker lubrication and better protection for an engine. This is especially important in modern cars with turbochargers which can run hotter and faster. As oil circulates it picks up deposits and conventional oil can form sludge—which will hurt performance and engine life.

Is Synthetic Worth It?

There isn’t a universal standard for choosing between synthetic and conventional oil but there are many things to take into consideration during the decision making process. Both synthetic and conventional blends have pros and cons when it comes to cost, time between service, and environmental conditions.

Mineral oils still do have lots of non-vehicle uses, and some people will still opt to put it in their cars to save money up front. However, it’s important to consider that synthetic oil allows you to go longer between oil changes, will likely improve engine performance and gas mileage, and extend engine life. These all point towards the initial investment in synthetic oil and synthetic blends to be worth it. This is especially true if your vehicles are heavy-duty or high-mileage.

Which Should I Use?

There is no clear answer to this question as it truly depends on:

• The type of vehicle and any manufacturer recommendations
• How it is being driven
• The pre-existing condition of the engine 
• The temperature environments the vehicle is subjected to

One smart way to save on both conventional and synthetic oil (especially if you’re responsible for a fleet of vehicles) is to purchase it in bulk.

With Keller-Heartt you get free delivery even on 55-gallon drums. Shop these popular Shell Rotella options to price compare and see what you can save.

Conventional: Shell Rotella T4 15W-40 Heavy Duty 

Synthetic blend: Shell Rotella T5 10W-30 Heavy Duty

Full Synthetic: Shell Rotella T6 5W-40 Heavy Duty for Diesel Engines

Another option for even more savings is buying Keller-Heartt’s own Truegard^® oils which provide the same level of protection as comparable blends and full synthetics.

Synthetic blend: Truegard® 15W-40

Full Synthetic: Truegard® 5W-30 

Got oil-related questions? We’d be happy to answer them. Contact us today to learn more about which diesel engine oil is right for you.