So i have been looking at the properties of what i'm currently running in my civic. It looks like it is a around 2cSt more visocous compared to Honda MTF and 5w20 alternative that they recommend in the manual. I've emailed Amsoil asking what they think about it and here are their replies: The AMSOIL MTF is going to be the best lubricant to use in this manual transmission. The use of engine oil would only be a temporary recommendation, and may be harmful if used for the long-term. Both AMSOIL MTF and Honda MTF are (5W)30 viscosity. The specifications for SAE 30 say the viscosity must fall within the range of 6.9 and 12.3 cSt at 100 deg. C. . This shows us that both oils fall into the same acceptable range. These are two different folks replying to my question. Obviously they ate wrong on Honda recommendation of 30 weight. That said, i kind of wonder, how are they recommending this fluid for this particular application if they don't even know what is Honda's spec? Thoughts?