As a trainer for Diamond, I’m frequently asked “What kind of hydraulic oil should I use for my mower?” Or “What brand of oil should I use?” Diamond Mowers recommends using an ISO 46 for all of our hydraulic oil applications.

What Does the ISO Number Mean?
Oil is available in many different weights, and each one works best for a particular application. Think of the difference between water and maple syrup. In this comparison, the water would have a low ISO number because it’s thin and flows easily at room temperature, while the syrup would have a high number because it is much thicker and flows easily.

The same is true with the ISO numbers of hydraulic oil. Some common weights of oil in the agriculture or construction industries would be ISO 32, ISO 46, and ISO 68. Diamond’s recommendation of ISO 46 is a mid-range weight of oil that lubricates well in both cold and hot environments.

What is the Correct Oil Weight?
The question of correct oil weight can arise when a dealership uses bulk oil that falls outside of our typical specification. Some dealers receive Hy-Gard in bulk at a discount compared to other types of oils. Although this has a slightly higher ISO rating (about ISO 56), it is still acceptable to use, especially in warmer climates such as the Southern United States in the summertime. It may, however, be a bit too thick to use in Northern Alaska or Canada in the wintertime.

Which Brand of Oil is Best?
The question of which brand of oil to use is really one of personal preference. As with most things in life, you usually get what you pay for. Be sure to purchase your oil from a supplier you can trust. By doing so, you are less likely to receive a product that is low-grade, or worse, contaminated.

In short, name brands of oil do not matter as long as you have a good, quality hydraulic oil with a mid-range weight for most applications.

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