How Often Should You Change Oil And How Do You Know It Needs Changed

How Often Should You Change Oil And How Do You Know It Needs Changed

One of the more controversial topics we hear discussed is something that has strongly varied opinions — what oil to use in a diesel engine and how often should you change that oil? Do a quick search on the internet, and those varied opinions can unsettle the thought process of even a seasoned diesel enthusiast.

Whether you’re driving a new diesel pickup truck, an older rig, or simply looking for more information, we will attempt to clarify this hot topic because as I said, there is no simple answer. In fact, diesel pickup owner, Lloyd Hunt, was facing this very confusing situation with his 2015 Super Duty. It was time for a change and while he knew the basics of what oil to use (viscosity), he really wanted to make sure he chose the correct lube. With so much information available on the internet, he thought it best to help clear the air, so he decided to reach out to the folks at AMSOIL to get a solid recommendation.

Solid Reasoning

There is no arguing that preventative maintenance is a very important thing every diesel owner needs to do for their truck. Sure, performance improvements are great, but you really need a good maintenance program to keep your truck running at its peak potential.

How often should you change oil

Oil change intervals have always been a hot topic among diesel owners. Maybe your opinion about the subject will change after reading this article.

“Unfortunately, there is not a one-size-fits-all answer to the question about how often you should change your oil,” says Brett Granmo, AMSOIL’S market manager – automotive B2B and HD on/off-road. “AMSOIL Heavy-Duty Synthetic Diesel Oil is recommended for the drain intervals stated by the original equipment manufacturer (OEM). However, intervals may be extended beyond the OEM recommended interval if an oil analysis is performed and the oil is deemed within specification. AMSOIL Signature Series Max-Duty Synthetic Diesel Oil line is our top-grade line and extended drain intervals are an option based on the type of equipment. However, users should refer to the product datasheet for full details. Intervals may be extended beyond the recommended intervals below with oil analysis.”

  • Heavy-Duty On-/Off-Road: Can remain in use up to three times OEM recommendation, not to exceed 60,000 miles/600 hours or one year, whichever comes first.
  • Turbodiesel Pickup: Two times the OEM recommendation, not to exceed 25,000 miles or one year, whichever comes first.
  • Competition Service Life: Provides lasting protection for multiple events. Use oil analysis to determine appropriate drain intervals.

Brett mentioned oil analysis, and I asked for a little more information about that. “An oil analysis is a great tool in providing a glimpse inside your engine to gauge lubricant and component condition without draining the oil. Oil analysis is simple, inexpensive, helps extend equipment life, prevents major problems, maximizes reliability, helps maximize drain intervals, and saves you time and money.”

To do an analysis, simply take a sample of the lubricant so technicians can do a range of tests to determine the concentration of wear metals, fuel dilution, the lubricant’s total base number (TBN), oxidation, and other information. The lab sends you a report that shows the lubricant condition and includes a brief explanation and recommendations for future service. Monitoring the condition of the oil allows you to optimize drain intervals so you can capitalize on the fluid’s service life.

Something not many truck owners think about is an oil analysis report. It's a good idea to add to your maintenance plan as it can help detect engine issues early. In Lloyd's situation, it made him aware of a fuel dilution situation that could have definitely caused serious engine damage if not addressed.

Oil analysis identifies dirt, wear particles, fuel dilution, coolant, and other contaminants that can cause catastrophic failure or significantly shorten equipment life. Arming yourself with this information allows you to proactively fix problems before they spiral out of control.

What Is Total Base Number

If you have never heard of an oil Total Base Number (TBN), don’t worry, it’s not something many people consider. TBN is a property that measures an oil’s ability to neutralize acids formed during engine operation. Generally, an oil with a higher TBN can better neutralize acidic materials and combustion by-products. This results in longer oil life and improved protection against corrosion. Since TBN measurements are an indicator of a lubricant’s capacity to neutralize acids, they are especially useful when wanting to extend oil drain intervals. The TBN of new oil is typically in the range of 7 to 10 for gasoline engines and 10 to 14 for diesel engines. If the TBN drops to a point where the oil can no longer neutralize acids, usually around 3, it typically indicates it is time for an oil change.

“AMSOIL sells oil analysis kits that someone can do themselves on our website Shop Used Oil Analysis Kits & Accessories – AMSOIL,”  Brett affirms. “You can also find more information at Oil Analyzers Inc. Oil Analysis & Oil Testing Services – Oil Analyzers, INC. (”

Getting It Right

With the various weights and designations available, how can a diesel owner know which AMSOIL products he or she needs? Brett replied, “if a diesel owner is looking for an upgrade over conventional, synthetic-blend, or synthetic, our recommendation is our AMSOIL Heavy-Duty Synthetic Diesel Oil line which is an advanced 100-percent synthetic formula. It is developed for hard-working equipment that provides four times more wear protection.”

“However”, Brett continues, “if a diesel owner wants the best product AMSOIL has, the Signature Series Max-Duty Synthetic Diesel Oil is our top-grade 100-percent synthetic diesel oil line. it provides six times more wear protection for maximum protection that goes above and beyond the standard, including reserve protection to extend the service interval if the customer chooses.”

how often should you change oil

If you’re looking for an oil upgrade over conventional or synthetic-blend oils, AMSOIL’s Heavy-Duty Synthetic Diesel Oil line which is an advanced 100-percent synthetic formula. The best product AMSOIL has is the Signature Series Max-Duty Synthetic Diesel Oil.

With this information in hand, Lloyd made the decision to do an oil analysis before the change. What he found was his oil was highly contaminated with fuel. While this is not a good thing, fortunately, it was not due to a mechanical issue. Fuel dilution occurs when unburned diesel fuel gets into your engine’s crankcase. As you would expect, this dilutes, or “waters down,” the oil. Once this happens, wear protection is exponentially decreased.

Fuel Dilution?

But how does the fuel get into the oil? There are a number of potential factors, including: leaking fuel injectors, excessive idling, incomplete combustion, continuously low engine temperatures, frequent short-trip driving, and/or worn piston rings, to name a few. After a thorough inspection, it was deemed that Lloyd’s frequent short drives to work had to be the culprit. It is safe to say that doing an analysis definitely saved Lloyd some major repairs down the road.

Although this article is about oil changes, I am not going to get into how to physically change the oil in your pickup, as you either already know and do it yourself or you pay a shop to do it for you. Either way, now you have some input about oil selection, suggested change intervals, and making sure you know how to properly maintain your engine’s lubrication requirements.

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About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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