 這個好像比較正確，我亂說的，參考就好。
這引擎機油好像只有告訴我們黏度，cst。centi-stoke
厚度，幾微米怎麼看，用手戳。μm
很正常 台灣都有奈米nm機油了。
正確答案應該是大家(人多)說得就算。搖一搖
留Thank you for sharing .. 就好了
討論區，沒有絕對誰說的就對或是錯。信仰問題。
只是那張圖只是截取 美國安索AMSOIL機油說道的一小部分。圖片應該有三張，反正看圖說故事。
Motorcycle Oil Shear Stability(機車機油剪切穩定性)
http://oilderek.com/learning%20center/Motorcycle/motorcycle_oil_shear_stabilty.htm
那個一扯又是弱弱長。
原文
Mechanical activity within an engine creates shearing forces that can negatively affect a lubricant’s protective viscosity. Even lubricants that provide consistent viscosity through a wide temperature range (high viscosity index) are susceptible to shearing forces that reduce viscosity and load carrying ability. Engines operating at high RPMs and those that share a common oil sump with the transmission are particularly subject to high shear rates. In fact, gear sets found in motorcycle transmissions are the leading cause of shear induced viscosity loss in motorcycle lubricants. The ASTM D-6278 Viscosity Shear Stability Test is used to determine a lubricant’s shear stability. After measuring its initial viscosity, the oil is subjected to shearing forces in 30 cycle intervals. Viscosity is measured and compared to the oil’s initial viscosity following 30, 90 and 120 cycles. The lower the degree of change, the better protection the lubricant provides against shearing forces.
Two separate tests were performed for SAE 40 and SAE 50 oils, with each grade split into two or three groups to make the graphs easier to reference. The flatter the line on the graph, the greater the shear stability of the oil. The results showed significant variances in shear stability protection. Within the SAE 40 group, 41.6 percent of the oils dropped one viscosity grade to an SAE 30, while 43.8 percent of the oils in the SAE 50 group dropped one viscosity grade to an SAE 40. The viscosity loss tended to occur quickly, with most of the affected oils dropping a viscosity grade within the first 30 cycles of shearing. In addition, it is interesting to note that two of the oils with the highest viscosity indices, Torco T-4SR in the SAE 40 group and Yamalube 4R in the SAE 50 group, exhibited the largest drops in viscosity in their respective test groups during shear stability testing.
As seen in the graphs, both AMSOIL 10W-40 Synthetic Motorcycle Oil (MCF) and 20W-50 Synthetic Motorcycle Oil (MCV) placed at the top of their respective test groups in the Viscosity Shear Stability Test, indicating that AMSOIL Synthetic Motorcycle Oils are the best choice for superior protection of motorcycle engines and transmissions.
該文章乃引擎機油廠商的實驗。
https://www.syntheticoilhq.com/harley-davidson-oilcomparison.html
蠻分散的。
而且年代久遠。
https://www.mobile01.com/topicdetail.php?f=266&t=1248121
在台灣看油，是很輕鬆。拿香跟拜就對了。不用管，規範。白皮書。甚至有沒有相關認證。好用，都看使用的自己的心得。手感。或是震動感，聲音。
https://www.astm.org/
美國材料和試驗協會，他對於大部人只是一個國際標準化組織。當然很多人(台灣)不相信測試方式。
至於ASTM 測試方式，放旁邊 太複雜了。
人們更相信。使用心得，或是製造(生產)商宣稱的效能。商業術語。
""Full synthetic" is a marketing term and is not a measurable quality."這句話很常在網路google 看到。不是我發明的。
本文最後由 pompom 於 2025-1-30 08:44 編輯
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