Hi. Im new to the classic car world coming from turboed imports. I just aquired a 1969 cutlass supreme. It has the 350/350 in it. Heres the problem. When its been sitting I can start it and it runs thru the gears perfectly. However after 10 mins or so as the car warms up I lose the transmission and it seems every gear becomes nuetral. It doeesnt engage again until I let it cool off a while and restart. Fluid is clean and topped off. Already drained some and addded TranX. Ive searched and found nothing like this, any ideas?

 

Try a new filter with all new fluid. My lincoln had the same problem, it was just the filter. Other than that, dont know that to tell ya sorry. Someone else will