I've used Amsoil's Synthetic Manual Synchromesh Transmission Fluid (the actual name of the product) for decades, going back to a time when Honda's manual transmission "fluid" (MTF) was, in fact, straight 5W-30 weight motor oil. IMHO, Amsoil's MTF is far superior to Honda's MTF, particularly in cold weather. (If you care to hunt around on BITOG, I've written about my experiences with both Honda's MTF and Amsoil several times over the years.)