Why Does My Truck Burn Oil? [And what to do about it]

Discovering that your truck is burning oil is never a welcome sign. This problem ranges from very serious to minorly inconvenient - but is very common. After reading a wide range of sources, we have come up with the following to help you understand why this can be happening.

Simply put, your truck is burning oil because of a hole or gap in the oil-containing part of the engine. These come in two main categories:

• A leak to within the combustion chamber, which leads to blue exhaust smoke.
• A leak in another part of the engine that is dripping on a hot engine part.

Both of these issues can be serious. Below we will provide a more in-depth answer on why your truck might be burning oil. This includes ways to determine the severity of the leak and whether to live with the leak or fix it. We will also touch on a few ways to potentially fix the problem and answer a few related questions.

Understanding Oil Loss and Oil Burning

Bad Seal or Damaged Part

It is common to discover that your truck is burning oil because of blueish smoke in the exhaust. The cause is likely due to a bad seal or damaged part near your truck’s combustion chamber. This means that oil is burning along with your gas or diesel and releasing through your exhaust system. Common sources are head gasket, piston rings, valve seals, or the positive crankcase ventilation valve. 

Leaks around the combustion chamber damage nearby parts (like spark plugs), lead to low oil levels and decrease fuel mileage. This type of problem is what mechanics officially refer to as “burning oil”. 

Leak Outside the Combustion Chamber

Your truck might also be burning oil because of a leak outside the combustion chamber. These leaks you can notice through observing an oil spill, wet spot, or a burning smell. Oil cooling lines, the oil pan, and the oil cap are just a few examples of potential sources. Only when the oil lands on especially hot engine parts, such as the exhaust system, do these leaks technically “burn” oil.

Why do Leaks Start?

Still, the question remains - Why do these leaks start in the first place? Well, engine parts must endure high pressure, heat, and lots of rapid movement. This, combined with dirty, sludgy oil and age, leads to small failure of parts. Usually, these leaks start around gaskets or rings, which are parts used to make joints liquid tight.

In terms of oil burning, the area around the combustion chamber must endure exceptionally high heat and rapid movement so developing leaks there is nearly inevitable. And unfortunately, once a tiny gap appears, the oil that slips through begins to wear it larger. For this reason, it is essential always to keep an eye on your oil level and address any problems as they arise.

To watch your oil level, regularly check your oil dipstick. This allows you to identify when leaks start and how severe they are. A good rule of thumb is that if the oil drops more than ¼ of the dipstick over a week of driving, your leak is severe. While checking your oil, be sure to refill whenever possible. Keeping your oil full is critical for the longevity of engine parts.

What to do if you suspect your truck leaks oil?

No matter the severity or location, all leaks should be dealt with. We recommend that a trained, certified mechanic completes repairs. By catching and fixing a problem earlier, you can often save yourself money in the long run.

How Much Oil Should You Lose Between Oil Changes?

Burning oil is just something that happens to trucks and is considered a normal part of engine operation. Generally speaking, a well-maintained truck should not lose more than one quart of oil between oil changes.

To find out how much oil your specific make and model should lose, check with your manufacturer. However, not all brands provide a clear answer to this. Either way, what is normal depends on engine size and vehicle age. A larger engine holds more oil, so it loses more just as an older car burns more as well.

Do Diesel Engines Consume More Oil Than Gas Engines?

While it is true that oil for diesel and gas engines are not the same, diesel engines do not as-a-matter-of-course burn more oil than their gas counterparts. The additional parts needing oil in a diesel engine, such as the turbocharger, do open up more potential trouble areas for leaks. What is “normal” still depends on the manufacturer’s specifications.

Is It Better To Use Thicker Engine Oil?

Every vehicle works with a specific type of oil. For instance, diesel and gasoline engines use oils with different amounts of additives and thickness. It might seem like using a thicker oil might plug up your oil leaks, but following manufacturer’s recommendations is the priority. 

Is There An Additive To Stop Oil Burning?

Slower leaks and hard to identify leaks can be fixed with a wide range of “oil leak stop” products. These oil additives travel throughout the oil system and fill in holes. Different products work on different leak locations and types. So knowing where the leak is, and how fast that leak is, will help make using these products more effective. 

Be careful, though, oil stop leak products have mixed results and can sometimes even gunk up engine parts. Read labels carefully and consult the staff at the auto parts store before using them at home. And as always, even after using these additives, be sure to check your oil levels regularly.

Summary

Oil loss and burning is a typical truck problem. Whether it is into the combustion chamber or in a different part of your oil system, oil leaks are essential to diagnose and understand quickly. While there are some potential do-it-yourself fixes, taking your rig into the mechanic is the surest bet to keep your truck running. As a final reminder, never stop regularly checking that dipstick to make sure you catch all oil problems before they become serious.