General Coolant Comparison

There are many different brands of coolants on the market today.  There are also many different types.  You hear things like micro emulsion and hybrid in addition to the traditional names.  Each manufacturer is claiming they have the next great thing.  Some of these claims may be true while many are not.  The goal of this page is to simply give you general information about the 3 main types of coolants.  My recommendation after that is to work with a company that specializes in the metalworking fluid field.  They will probably be best suited to help you with specific situations and issues.

Soluble Oil

Soluble oils are manufactured using mineral oil.  Their major component is mineral oil.  Many components can be added to enhance sump life, tool life and foam control.  Soluble oils are typically very milky when mixed with water.  They tend to have a little more residue than the other types.  Sump life can be pretty good but usually they don’t last as long as the semi-synthetics or the synthetics.  Because the major component is mineral oil, sometimes more extreme pressure additives can be included to enhance tool life.  Anti-foam can be added but they typically do not hold up in high pressure without producing an excessive amount of foam.  Soluble oils usually have pretty good rust protection.

Semi-Synthetic Coolant

The semi-synthetic/hybrid/micro emulsion is usually a combination of the soluble and synthetic technology.  It contains mineral oil but it usually is not the major component.  There are high oil and low oil semi-synthetics.  This type of coolant is usually somewhat translucent when mixed with water.  They typically have better foam control than soluble oil and can have longer sump life.  High oil semi-synthetic fluids can hold a lot of the same extreme pressure additives of a soluble to give you good tool life on the harder metals.  Semi-synthetics usually have good rust protection.

Synthetic Coolant

Synthetic coolants usually do not contain any mineral oil.  They are formulated using a litany of chemicals to produce rust protection and tool life.  There is the conventional type and there is the newer oil rejecting type.  Both products are clear when mixed with water.  The conventional type will usually emulsify oil and therefore will become milky over time.  This in turn means they can go rancid.  The new oil rejecting type will not emulsify oil and therefore usually have extremely long sump life.  The conventional type will usually foam in high pressure while the newer oil rejecting type has very good low foam characteristics.  The advantage of the conventional type is they are very low cost.  The advantage of the newer oil rejecting type is they have extremely long sump life, have very good low foam characteristics and also run very clean.  Synthetic coolants usually don’t have the same rust protection as the soluble or semi-synthetics.  They are also harder on the machines because they do not contain any oil.  Most synthetics are best for your medium to light duty metals.  Many of the extreme pressure additives used for hard metals cannot be added.

Typical Characteristics

I know this is a very broad description of the different types of fluids.  Many products will produce different results based on the additives and formulations.  Over the years, I have had products that companies love while others hated them.  Each shop is different and I would recommend having a person come out to evaluate your particular situation so they can recommend a product that will suit your needs.  Metalworking fluids take years to learn.  I have specialized in this field for many years and I am still learning today.