A few months ago I acquired a 740T with an M-46 and have a few questions. First of all, thank you all who contributed to the 700/900 FAQ. It has been a wealth of info for years. Secondly,since this post is about manual transmissions I thought I'd mention that Auto Zone has Castrol Type F on clearance for 1.99 That is,in S.Ca. anyway. I topped off the tranny with type F recently and it occurred to me that I had no idea whether F or a synthetic 10W30 was in it. How would these two mix? I need to drain all the fluid and refill with F or perhaps a synthetic blend of F and Redline. When I topped it off I took a tip from the FAQ. --[Tony Hoffman] The M-47 takes 1.6 quarts. By jacking up the driver's side, you can insert all 2 quarts, overfilling slightly above the fill hole's normal line and ensure that fifth gear has more than adequate lubricant. [Ryan R.] The word on the street is that the M-47 fill hole is two low, so the 5th gear eventually wears out. The over fill with 2 quarts seems to work.--I mentioned that I had overfilled my trans to a fellow Brickster and he seems to think that overfilling leads to "problems" but didn't say what those problems might be. I can't imagine suggesting overfilling in the 7/9 FAQ if it wasn't consensus that doing so is okay, but thought I'd ask if anyone has encountered a problem doing so.