Mixing different oil grades in your semi truck

3 min read
Mixing different oil grades in your semi truck

A semi-truck is a workhorse that requires careful maintenance and is more than just a car. It is an expensive piece of equipment. Oil mixing is one topic that frequently sparks a lot of discussion and misunderstanding. Is it an area of truck maintenance that can be approved or prohibited? Let's examine the facts and fiction surrounding oil-grade mixing in semi-trucks in greater detail.

Knowing the Viscosity of Oil

Understand what oil viscosity is before we talk about mixing. The thickness or flow resistance of a fluid is referred to as its viscosity. Consider it this way: honey flows more slowly than water, so it has a higher viscosity than water. Similar to this, engine oils are made with particular viscosities in mind to guarantee that they provide the best lubrication possible at various temperatures. The grades, such as 5W-30, indicate the viscosity property.

Is that okay? Can drivers do it?

Yes, in short, but with some qualifications. In an emergency, blending different oil grades won't necessarily damage your engine. However, it's crucial to comprehend the repercussions and the reasons why following the manufacturer's instructions is usually preferable.

What Happens When You Mix Different Viscosities?

Consider yourself mixing a drink. By combining two ingredients in the right proportion, you can make a tasty beverage. However, if you combine them carelessly, the outcome might not be very pleasant. Likewise with oils.

The performance characteristics of the resulting oil can change when two different viscosities are mixed. In extremely hot or cold temperatures, this blend might not behave as you would expect and might not offer enough protection against wear. Therefore, while a one-time mix won't cause the engine to blow up, doing so repeatedly could hasten wear and reduce engine efficiency.

Concealing Oil Brands

The oil brand controversy dates back as far as the hills. Although each brand formulates engine oils differently, modern engine oils are typically interchangeable. It won't damage the engine if you need to top it off and can only get a different brand. However, because every brand uses a different set of additives, it's best to stick with a single brand and formulation for optimal results.

Can you combine 10w30 with 5w20 and 5w30 with 5w40?

10w30 and 5w20

The viscosities of these two oils differ at both operating and cold temperatures. The resultant oil will lie in the middle of each of their individual viscosities, but combining them won't have disastrous consequences. In extreme cold or extreme heat, it might not offer as much protection as a pure oil grade.

Using 5w30 and 5w40

The viscosities of these oils vary at operating temperatures, but they have the same cold-start viscosity. At operating temperature, mixing them would result in an oil with a viscosity of between 30 and 40. Although there isn't as much of a deviation as with the previous mix, using a consistent grade is still advised for the best outcomes.

In summary

Mixing oil grades isn't the biggest sin in the grand scheme of semi-truck maintenance, but it's also not a habit to get into. Although you can get away with it in an emergency, it's best to follow the manufacturer's recommendation for your truck's long-term health and performance. It's always better to be safe than sorry when it comes to the engine that powers your semi-truck. A safe journey!