Hello,

The overdrive on my trusty 86 740 with 200K and an M46 manual transmission is not working properly. When the car is cold (for about the first 3 miles on the highway) it goes into OD with no problem. After it warms up the OD disengages partially such that the engine RPM can be anywhere between idle and the value for 4th gear. The 5th gear light remains on until I push the botton. I have replaced the OD relay and cleaned up the connections to the solenoid. I have also cleaned the screens in the transmission and filled with Redline Supershift fluid (I think that the redline actually made the OD problem worse, but shifting through other gears is smoother). I am thinking about filling with ATF type F again and hoping for the best. I think that it is probally a low pressure issue due to leaking seals within the transmission, but what do you think? It would seem that a thicker fluid would minimize the leaking around the seals and increase the pressure. Is there a brand or type of ATF F that is thicker than others? I would love to find a thicker synthetic fluid.

If I do need a rebuild, where should I take it? I want an excellent job done - like I had the time or space to do it myself. I live in New York City, but could also have the work done in Philadelphia, where my parents live.

Thank you,
Steve
--
1986 745 w/ M46 200K since new, 1995 965 104K