# Best ISO VG 32 vs 46 vs 68 Hydraulic Oil: Differences, Uses & Selection Guide **By Rahul Gupta** · 2026-10-21 # Best ISO VG 32 vs 46 vs 68 Hydraulic Oil: Differences, Uses & Selection Guide ## Introduction Choosing the right hydraulic oil is essential for maintaining the performance and reliability of industrial machinery. Whether you operate a hydraulic press, injection moulding machine, power pack, manufacturing equipment or other hydraulic system, selecting the correct viscosity grade helps ensure that the oil flows properly under operating conditions. Among the commonly used industrial viscosity grades, **ISO VG 32, ISO VG 46 and ISO VG 68 hydraulic oil** are important options for different equipment requirements. Although these grades may look similar, they differ in viscosity, which influences oil flow, lubrication and hydraulic system performance. So, what is the difference between ISO VG 32, 46 and 68? Which grade is suitable for your machinery, and how should you select the right industrial oil? In this guide, Bharat Lubricants explains the differences between these ISO viscosity grades, their typical applications and the key factors to consider before purchasing hydraulic oil. ## What Is ISO VG in Hydraulic Oil? ISO VG stands for **International Organization for Standardization Viscosity Grade**. It is a classification system used to identify industrial lubricants according to their kinematic viscosity at 40°C, as defined by ISO 3448. Viscosity describes a fluid's resistance to flow. In simple terms, a lower-viscosity oil flows more easily at the same temperature, while a higher-viscosity oil offers greater resistance to flow. The ISO VG number represents the nominal viscosity in centistokes (cSt), equivalent to mm²/s, at 40°C. It does not indicate the overall quality of the oil, its additive package or whether it meets a particular hydraulic system's performance requirements. For example: - **ISO VG 32:** Nominal viscosity of 32 cSt at 40°C. - **ISO VG 46:** Nominal viscosity of 46 cSt at 40°C. - **ISO VG 68:** Nominal viscosity of 68 cSt at 40°C. ISO VG 32 is the least viscous of these three grades, while ISO VG 68 is the most viscous. The correct choice depends on the equipment manufacturer's specifications and actual operating conditions. ## ISO VG 32 vs 46 vs 68 Hydraulic Oil: Comparison Chart The following table compares the three grades according to the ISO viscosity classification. Parameter ISO VG 32 ISO VG 46 ISO VG 68 Nominal viscosity at 40°C 32 cSt 46 cSt 68 cSt ISO viscosity range at 40°C 28.8–35.2 cSt 41.4–50.6 cSt 61.2–74.8 cSt Relative viscosity Lower Medium Higher General flow characteristics Flows more easily Intermediate viscosity Greater resistance to flow Typical selection consideration Systems requiring a lower viscosity grade General industrial systems specifying VG 46 Systems requiring a higher viscosity grade Final selection Follow equipment specifications Follow equipment specifications Follow equipment specifications _Note: The viscosity ranges shown are the ISO 3448 classification limits, not measured specifications for every commercial oil._ ## 1\. ISO VG 32 Hydraulic Oil: Features and Applications ISO VG 32 hydraulic oil is a lower-viscosity grade compared with ISO VG 46 and ISO VG 68. It may be suitable for hydraulic equipment designed to operate with relatively lower-viscosity oil. Its flow characteristics can be useful in systems where the manufacturer specifies this grade and where operating temperatures and pump requirements support its use. ### Common application considerations ISO VG 32 may be considered for: - Hydraulic power packs designed for VG 32. - Industrial machinery requiring lower-viscosity hydraulic oil. - Selected mobile hydraulic systems. - Equipment operating under conditions where the specified oil viscosity is relatively low. ### When should you choose ISO VG 32? Consider ISO VG 32 when the machine manual, pump manufacturer or lubrication specification explicitly recommends this grade. Also check the equipment's permissible viscosity range at startup and normal operating temperature. A lower ISO VG number does not automatically mean better performance in cold weather. Actual low-temperature behaviour also depends on the oil formulation, viscosity index and pour point. ## 2\. ISO VG 46 Hydraulic Oil: Features and Applications ISO VG 46 hydraulic oil has a nominal kinematic viscosity of 46 cSt at 40°C. It sits between VG 32 and VG 68 and is commonly encountered in industrial hydraulic applications. Where equipment is designed for VG 46, this grade provides the viscosity characteristics specified for the system's operating requirements. ### Common application considerations ISO VG 46 may be suitable for: - Industrial hydraulic power packs. - Hydraulic presses and manufacturing machinery. - Injection moulding equipment that specifies VG 46. - Hydraulic systems used in general industrial operations. - Other machinery requiring an ISO VG 46 hydraulic fluid. ### Why is ISO VG 46 widely considered? Many industrial buyers encounter VG 46 when sourcing hydraulic oil for factory machinery. However, its popularity does not mean it is the right choice for every hydraulic system. Before purchasing, verify the specified viscosity grade, required hydraulic oil category, additive requirements and any equipment manufacturer approvals. For machinery requiring VG 46, choosing an oil that meets the complete specification is more important than selecting a grade based only on general industry practice. ## 3\. ISO VG 68 Hydraulic Oil: Features and Applications ISO VG 68 hydraulic oil has a nominal kinematic viscosity of 68 cSt at 40°C, making it the highest-viscosity grade among the three compared here. It may be appropriate for hydraulic systems designed to operate with a higher-viscosity oil, provided the oil remains within the equipment's permissible viscosity limits throughout operation. ### Common application considerations ISO VG 68 may be considered for: - Industrial hydraulic systems specifying VG 68. - Hydraulic power units designed for higher-viscosity fluid. - Selected presses and heavy industrial machinery. - Manufacturing equipment whose operating requirements call for VG 68. ### When should you choose ISO VG 68? Choose VG 68 when the equipment specification calls for this grade or the manufacturer confirms it is suitable. Do not select VG 68 simply because a machine operates in a hot environment or handles heavy loads. Excessive viscosity can restrict flow, increase pumping losses and create startup problems. The actual oil temperature, pump design and operating viscosity limits must be considered. ## Key Differences Between ISO VG 32, 46 and 68 Understanding the practical differences makes it easier to identify which product to investigate for your application. ### Difference in viscosity The primary difference is the nominal viscosity at 40°C. VG 32 is less viscous than VG 46, and VG 46 is less viscous than VG 68. This difference affects the resistance the oil offers to flow through pumps, valves, pipes and other hydraulic components. ### Difference in oil flow At the same temperature, VG 32 generally flows more easily than VG 46 and VG 68. Higher-viscosity oil offers greater resistance to flow. However, flow through an actual hydraulic system also depends on pressure, temperature, pump design, line dimensions and other operating conditions. ### Difference in equipment suitability Each grade is intended for equipment operating within a particular viscosity range. Using an unsuitable grade can affect lubrication, hydraulic response and overall system performance. Always check the equipment manual instead of switching grades based solely on a general comparison. ### Difference in product formulation ISO VG identifies viscosity, not the complete oil formulation. Two oils with the same ISO VG grade may differ in base oil, additives, viscosity index, oxidation stability and anti-wear performance. For hydraulic applications, verify whether the equipment requires a particular category, such as an anti-wear hydraulic oil, and whether the product meets the relevant specifications. ## How to Choose the Right ISO VG Hydraulic Oil Selecting hydraulic oil requires more than comparing the numbers printed on the container. Consider these factors before placing an order. ### 1\. Check the equipment manufacturer's recommendation Start with the machine manual, lubrication chart or hydraulic pump documentation. Confirm the required ISO VG grade and any specified oil category or performance standard. ### 2\. Consider operating temperature Hydraulic oil viscosity changes with temperature. Oil generally becomes less viscous as it heats and more viscous as it cools. Select a grade that remains within the equipment's permitted operating viscosity range during startup and normal operation. The ISO VG number alone does not establish suitability for a particular climate. ### 3\. Verify the hydraulic oil specification Check whether the equipment requires an anti-wear hydraulic oil or another specific formulation. Where applicable, review the stated standards, performance levels and manufacturer approvals on the product technical data sheet. ### 4\. Understand the machine's operating conditions Consider the pump type, operating pressure, duty cycle, load, fluid temperature and filtration requirements. These factors can influence the correct oil selection. ### 5\. Compare technical data sheets Before purchasing, review the product's kinematic viscosity at 40°C and 100°C, viscosity index, flash point, pour point and other relevant properties. Compare the published specifications with the machine manufacturer's requirements rather than assuming all products with the same ISO VG number are identical. ## What Happens If You Use the Wrong Hydraulic Oil Grade? Using a viscosity grade that does not match the equipment's requirements can create operating problems. **If the oil is too low in viscosity:** - The oil film may become insufficient under certain operating conditions. - Internal leakage may increase in components designed for a higher viscosity. - Lubrication and equipment efficiency may be affected. **If the oil is too high in viscosity:** - Oil circulation may become more difficult, particularly during startup. - Pumping losses may increase. - The system may experience restricted flow or other problems if viscosity exceeds permitted limits. The exact consequences depend on the hydraulic system design, oil formulation and operating conditions. If a machine develops abnormal noise, overheating or slow movement, check the oil grade alongside fluid condition, filters, pump health and other possible causes. ## Where Can You Buy ISO VG 32, 46 and 68 Industrial Oil in India? For industrial buyers, selecting the right viscosity grade is only one part of purchasing the correct lubricant. It is also important to check product specifications, packaging options, supply requirements and suitability for the intended application. Bharat Lubricants offers a range of industrial ISO grade oils for buyers looking for different viscosity options. You can explore the available grades and product listings directly through the official website. **Explore ISO Grade Oils from Bharat Lubricants:** [View ISO Grade Oil Products](https://www.bharatlubricants.com/collections/iso-grades) When enquiring about a product, share the required ISO VG grade, application, quantity and any technical specification provided by your equipment manufacturer. This information helps identify the appropriate product for your requirement. Whether you are purchasing for factory maintenance, industrial machinery or regular lubricant procurement, verify the specific product data sheet before confirming your order. ## Frequently Asked Questions About ISO VG 32, 46 and 68 ### 1\. What is the difference between ISO VG 32, 46 and 68 hydraulic oil? The primary difference is viscosity at 40°C. ISO VG 32 has a nominal viscosity of 32 cSt, VG 46 has 46 cSt, and VG 68 has 68 cSt. The appropriate grade depends on the hydraulic equipment's specifications and operating conditions. ### 2\. Which is thicker, ISO VG 32 or ISO VG 46? ISO VG 46 is more viscous than ISO VG 32 at the same reference temperature of 40°C. ### 3\. Is ISO VG 68 thicker than ISO VG 46? Yes. ISO VG 68 has a higher nominal kinematic viscosity than ISO VG 46 at 40°C. ### 4\. Can I replace ISO VG 46 with ISO VG 68? Not automatically. Changing from VG 46 to VG 68 changes the oil's viscosity and may affect flow and equipment operation. Use VG 68 only when the machine manufacturer confirms that it is suitable. ### 5\. Is ISO VG 32 suitable for hydraulic power packs? It can be suitable for power packs designed to operate with VG 32. Check the pump manufacturer's recommended viscosity grade and operating limits before using it. ### 6\. Does ISO VG 46 mean the oil is better quality than ISO VG 32? No. ISO VG numbers indicate viscosity classification, not oil quality. Product quality and suitability depend on the formulation, performance specifications, additive package and compliance with equipment requirements. ### 7\. What does ISO VG 68 mean? ISO VG 68 is an industrial lubricant viscosity grade with a nominal kinematic viscosity of 68 cSt at 40°C. It is used where the equipment specification requires this viscosity grade. ### 8\. Where can I buy ISO VG 32, 46 and 68 oil online? You can explore the available industrial ISO grade oils from Bharat Lubricants through the [official ISO Grades collection](https://www.bharatlubricants.com/collections/iso-grades). Check each product listing for its specifications, packaging and current availability. ## Conclusion ISO VG 32, ISO VG 46 and ISO VG 68 are three distinct industrial viscosity grades, each intended for equipment with specific lubrication requirements. VG 32 has the lowest nominal viscosity, VG 46 falls in the middle, and VG 68 has the highest nominal viscosity of the three. The right selection depends on the equipment manufacturer's recommendations, operating temperature, hydraulic system design and required oil performance specification. Before ordering, compare the product's technical data with your machinery's requirements and confirm that the selected oil is suitable for the application. **Looking for industrial ISO grade oil?** Explore the available products from Bharat Lubricants and find the grade that matches your equipment specification. [Explore ISO Grade Oils at Bharat Lubricants](https://www.bharatlubricants.com/collections/iso-grades) * * * **About Bharat Lubricants** Bharat Lubricants is an Indian lubricant brand established in 1984 in Surat, Gujarat, offering lubricant solutions for industrial and automotive applications. Visit the official website to explore available products and technical information. * * * ## Related Reading - [Best Industrial Lubricants Manufacturer in India: A Complete Guide to Industrial Oils](https://www.bharatlubricants.com/blogs/news/best-industrial-lubricants-manufacturer-in-india-a-complete-guide-to-industrial-oils) - [Best Grease Manufacturers in Gujarat: How to Choose the Right Grease](https://www.bharatlubricants.com/blogs/news/grease-manufacturers-in-gujarat) - [Industrial Grease Manufacturers in India](https://www.bharatlubricants.com/blogs/news/industrial-grease-manufacturers-in-india) ## 📲 Follow Bharat Lubricants Stay updated with the latest product launches, maintenance tips, industry insights, and lubrication guides. **📸 Follow us on Instagram:** 👉 [https://www.instagram.com/bharatlubricants/](https://www.instagram.com/bharatlubricants/ "Best industrial oil manufacturer in india") Looking for a trusted engine oil manufacturer in India? Visit [**Bharat Lubricants**.](https://www.bharatlubricants.com/ "Best lubricant manufacturer in india") **Tags:** AW 32 hydraulic oil, AW 46 hydraulic oil, AW 68 hydraulic oil, HLP 32 hydraulic oil, HLP 46 hydraulic oil, HLP 68 hydraulic oil, hydraulic oil for CNC machines, hydraulic oil for injection moulding machines, hydraulic oil manufacturer India, hydraulic oil supplier India, hydraulic oil viscosity grades, ISO VG 32 hydraulic oil, ISO VG 32 vs 46 vs 68, ISO VG 46 hydraulic oil, ISO VG 68 hydraulic oil --- > Source: [Bharat Lubricants](https://www.bharatlubricants.com/blogs/news/iso-vg-32-vs-46-vs-68-hydraulic-oil)