Can mechanical oils with different viscosities be mixed?

No, follow the instructions to extend the service life

It depends on the circumstances; it can’t be said that it’s completely impossible. In winter, as temperatures drop, the viscosity of oil increases. Using 46# oil in such conditions makes it difficult to remove heat in the same way as during summer, so an oil with slightly lower viscosity should be used

Mixing mixtures of the same model but with different viscosities results in a reduced viscosity; such mixing is generally not allowed, and mixing of different models is strictly prohibited.

Mixing is not recommended. If mixing is necessary, it is recommended that your analysis department conduct an analysis of the oils to determine whether mixing is possible. I’d like to ask gently: Is there such an excessive request? If that’s indeed the case, equipment manufacturers could consider oil coolers during design. Since you didn’t raise this issue before the equipment was installed and handed over, you can now carry out technical modifications by adding a small oil cooler; it doesn’t require much investment.

I also murmured to myself: It’s strange why the manufacturer of this pump still makes distinctions between summer and winter. Isn’t the main difference the temperature change? Why not install an electric heater on the mailbox? What kind of design is this? By keeping the temperature of the mailbox under control, you can use the same oil all the time

The last edit to this post was made by cjhti on 2010-11-13 at 22:19. Management of Lubricant Use (I) Selection of Lubricants The selection of lubricants is the first step in their use, and it is crucial for ensuring proper lubrication of equipment as well as maximizing the performance of the lubricants. 1. When selecting lubricating oil, the following three factors should be considered comprehensively: (1) the operating conditions under which the mechanical equipment is actually used (i.e., the working conditions) ； 　　(2) Designation or recommendation in the manufacturer’s instructions for mechanical equipment ； 　　(3) Regulations or recommendations from lubricant manufacturers. 2. Selection of lubricant performance indicators (1) Viscosity: Viscosity is the indicator used for classifying and grading various lubricants, and it is decisive for quality assessment and determination. The viscosity of the lubricating oil for equipment is determined by referring to relevant charts based on design or calculation data. 　　(2) Pour point is an indicator that indirectly represents the low-temperature fluidity of lubricants during storage, transportation, and use. Experience has shown that the operating temperature of general lubricants must be 5–10 °C higher than their pour point. 　　(3) Flash point: The flash point is primarily an indicator of the safety of storing, transporting, and using lubricants; it also serves as a criterion for controlling the fractions and volatility of lubricants during production. The principle governing the flash point specification for lubricants is to apply a safety factor of 1/2 in accordance with safety regulations, meaning the value is set 1/2 higher than the actual operating temperature. Since the oil temperature in the crankcase of internal combustion engine oils should not exceed 120 ℃, it is specified that the flash point of such oils must be at least 180 ℃. 　　(4) Selection of performance indicators: There are numerous performance indicators, and the differences between different varieties are significant; a reasonable decision should be made by taking into account the operating conditions of the equipment, the requirements of the manufacturer, as well as the specifications and descriptions related to the oil. Strive to meet the requirements of lubrication technology while remaining cost-effective. (II) Substitutes for lubricating oil 1. Different types of lubricating oils have their own specific characteristics or differences in terms of performance. Therefore, it is necessary to select lubricants correctly and appropriately, avoid using substitutes, and under no circumstances permit random substitution. 2. Principles for substituting lubricating oils (1) Try to use oils of the same type or those with similar properties as substitutes. 　　(2) The viscosity must be comparable; the viscosity of the substitute oil shall not exceed ±15% of that of the original oil. Oils with slightly higher viscosity should be given priority for substitution. 　　(3) Quality shall be higher rather than lower. 　　(4) When selecting alternative oils, attention should also be paid to the equipment’s operating environment and temperature. (III) Mixing of lubricants 1. It is advisable to avoid mixing lubricants of different types, grades, from different manufacturers, as well as old and new lubricants. The following oils must never be mixed together. (1) Military specialty oils and specialized fuels must not be mixed with other types of oils. 　　(2) Oils with anti-emulsification requirements must not be mixed with oils that do not have such requirements. 　　(3) Anti-ammonia turbine oil must not be mixed with other turbine oils. 　　(4) Zn-containing anti-wear hydraulic oil cannot be mixed with silver-resistant hydraulic oil. 　　(5) Gear oil must not be mixed with worm gear oil. 2. The following situations allow for mixing: (1) Products of the same manufacturer with similar quality and basic characteristics. 　　(2) Products of the same type but different grades from the same manufacturer. 　　(3) For oils of different types, provided it is known that neither component in the mixture contains additives. 　　(4) When oils of different types are mixed together, no abnormal phenomena or significant changes in performance occur. 3. There are a large variety and quantity of additives added to diesel engine oils, with varying performances ； Care must be taken when mixing oils with unknown performance characteristics. To avoid adverse consequences or even equipment lubrication failures.

This is quite normal. If everything is working properly, then it’s fine; the difference isn’t very significant. Many oils don’t need to be changed, as they perform similarly in winter and summer. But if you conduct tests, you’ll find that oils with different viscosities actually make a big difference in practical use, and that difference has a significant impact

It’s necessary to correct the comments made by a few fellow travelers upstairs. The manual for the W5-1 vacuum pump states that 60# mechanical oil should be used in summer, while 40# mechanical oil should be used in winter. Those are old grade specifications; we have been using 46# oil instead (which is a new grade). The manual refers to the old viscosity grades, based on the dynamic viscosity at 50 degrees Celsius. 60# corresponds to N100, while 40# corresponds to N68; 30# is what the original poster referred to as 46# (N46). Therefore, the viscosity of the lubricant with grade 46# (N46) used by the original poster is already low, and it is not appropriate to use a lubricant with an even lower viscosity.

Here is a comparison table of new and old grade numbers along with viscosity coefficient ranges for your reference: Mechanical oils are now referred to as oils for fully loss systems. The original national standard GB443-64 specified that lubricants should be classified into different grades based on the average value of their dynamic viscosity at either 50°C or 100°C. The new national standard GB443-84 specifies that the central value of the dynamic viscosity of the lubricant at 40°C shall be used as the new grade designation for the lubricant. The actual dynamic viscosity of the lubricating oil should be within a deviation of ±10% of the central viscosity value. The comparison of new and old grades of oils (machine oils) commonly used in fully lossy systems is shown in the table below. Comparison table of new and old grades and viscosity range values for oils used in fully lossy systems. Grade, Kinematic viscosity range, New, Old: 40°C, 50°C. L-AN5, Grade 4: 4.14–5.06, 3.32–3.99; L-AN7, Grade 6: 6.12–7.48, 4.76–5.72; L-AN10, Grade 7: 9.00–11.0, 6.78–8.14; L-AN15, Grade 10: 13.5–16.5, 9.80–11.8; L-AN22: –, 19.8–24.2, 13.9–16.6; L-AN32, Grade 20: 28.8–35.2, 19.4–23.3; L-AN46, Grade 30: 41.4–50.6, 27.0–32.5; L-AN68, Grade 40: 61.2–74.8, 38.7–46.6; L-AN100, Grade 60: 90.0–110, 55.3–66.6; L-AN150, Grade 90: 135–165, 80.6–97.1