What Viscosity of White Mineral Oil Do I Need? A Buyer’s Guide

Choosing the right white mineral oil isn’t only about deciding between food grade and technical grade.

You also need the right viscosity.

Viscosity affects how easily mineral oil flows, how it coats a surface, how it moves through equipment and how it performs in a particular application.

So, what viscosity of white mineral oil do you need?

The answer depends primarily on what you’re using it for and the performance you need from the oil.

What Does Mineral Oil Viscosity Mean?

Viscosity is simply a measure of a liquid’s resistance to flow.

A lower-viscosity mineral oil is thinner and flows more easily.

A higher-viscosity mineral oil is thicker and flows more slowly.

Think about the difference between water and honey. Both are liquids, but their flow characteristics are very different.

White mineral oils work the same way. Selecting the right viscosity helps the oil perform properly for the intended application.

What Are Common White Mineral Oil Viscosities?

STEOIL’s Crystal Plus® white mineral oil line includes multiple viscosities in both food-grade and technical-grade products.

These include:

Crystal Plus 70 — a lighter-viscosity mineral oil
Crystal Plus 200 — a medium-viscosity mineral oil
Crystal Plus 350 — a higher-viscosity mineral oil
Crystal Plus 500 — one of the heavier-viscosity options in the Crystal Plus line

Different applications require different flow, lubrication, coating and processing characteristics, which is why there isn’t one viscosity that works for every use.

When Is a Lower-Viscosity Mineral Oil Used?

Lower-viscosity white mineral oils are useful when an application requires easier flow, spreading or penetration.

Depending on the grade and regulatory requirements, applications can include cosmetics and personal care products, manufacturing processes, rust prevention, certain food-processing applications and other uses requiring a lighter oil.

Lower viscosity can also make an oil easier to pump or transfer under certain operating conditions.

When Is a Higher-Viscosity Mineral Oil Used?

Higher-viscosity mineral oils are thicker and may provide greater coating, lubrication or barrier characteristics.

They can be appropriate for applications such as certain plastics manufacturing processes, pelletizing, processing aids and other uses where a heavier oil is desirable.

The correct viscosity should always be determined by the requirements of the specific application.

Does Higher Viscosity Mean Better Mineral Oil?

No.

A higher viscosity doesn’t mean the oil is higher quality.

It simply means the oil has different flow characteristics.

Using an oil that is too thick can create problems just as using one that is too thin can.

The goal is not to purchase the highest viscosity available. The goal is to purchase the correct viscosity for the application.

What Information Helps Determine the Correct Viscosity?

If you’re unsure which viscosity you need, start by gathering a few pieces of information:

• What will the mineral oil be used for?
• Is the application food related or industrial?
• Will the oil be pumped, sprayed, circulated or applied directly?
• What temperatures will the oil encounter?
• Is it being used primarily for lubrication, coating, processing or another purpose?
• Are you replacing an existing mineral oil?
• Do you have a specification or technical data sheet for the oil currently being used?

If you’re replacing an existing product, providing the supplier with the current product name or specifications can be particularly helpful.

What Is the Difference Between SUS and cSt?

Mineral oil viscosity may be expressed using different measurements.

SUS, or Saybolt Universal Seconds, measures how long it takes a specified amount of fluid to flow through a calibrated opening at a particular temperature.

cSt, or centistokes, is a measurement of kinematic viscosity and is another common way of describing oil viscosity.

This is why a technical data sheet may include viscosity measurements at specific temperatures rather than simply describing an oil as light, medium or heavy.

Frequently Asked Questions About Mineral Oil Viscosity

Is 70 viscosity mineral oil thinner than 350?

Yes. Within the Crystal Plus product family, 70 represents a lighter-viscosity product than 350.

Does temperature affect mineral oil viscosity?

Yes. Like most oils, mineral oil becomes less viscous as temperature increases and more viscous as temperature decreases. Operating temperature should therefore be considered when selecting an oil.

Can I substitute one mineral oil viscosity for another?

Not automatically. Changing viscosity can affect how an oil flows and performs. The requirements of the application should be evaluated before making a substitution.

Are food-grade and technical-grade mineral oils available in different viscosities?

Yes. STEOIL offers Crystal Plus white mineral oils in multiple viscosities and in both food-grade and technical-grade options.

How do I determine the viscosity of the mineral oil I currently use?

Check the product’s technical data sheet or specification. If you’re unsure how to interpret the information, provide the documentation to your mineral oil supplier.

Don’t Choose Mineral Oil Based on Viscosity Alone

Viscosity is important, but it is only one part of selecting the right white mineral oil. Grade, purity requirements, regulatory requirements, application, operating conditions and packaging should also be considered.

If you’re uncertain which Crystal Plus® white mineral oil is right for your application, contact STEOIL and tell us what you’re trying to accomplish. We can help you evaluate your requirements and identify an appropriate product.