I know these questions have been asked in the past, but I'm having all kinds of trouble with the search function tonight. I'm working on my dad's '56 Fairlane in the morning. Engine is a 292 with an automatic transmission. The car has sat up for about a year and I'd like to get it back on the road for him while the weather is nice. My questions are: 1) What weight oil is needed? I know I used Motorcraft diesel oil last, I just don't remember the weight. 2) What kind of transmission fluid will I want to buy? It is the original automatic transmission. 3) The car is rarely driven, but does leak transmission fluid. Can some kind of stop leak be added until I can convince dad to have the transmission rebuilt? I do not know that either of the previous owners had the transmission rebuilt.
For oil, I use "Rotella T" 15-40 weight, and a pint of STP. This gives the proper weight and plenty of ZDDP to fight lifter/cam wear in pushrod motors. I use this in all my early pushrod-style motors and have for years. I think you'll like it. All my automatics are GM which use Dexron/Mercuron, but this does not apply to your early Ford auto*******. Others here on the board will have good advice on which transmission fluid is best for your car I'm sure.
Motorcraft 15W40 has more ZDDP than the new Rotella by 300ppm,stick with it.This companies product seems to work well:http://www.goldeagle.com/products/productE6EE.aspx for transmission fluid,You might want to check out this discussion: http://www.fordbarn.com/forum/showthread.php?t=65814 about fluids.
I have two a 54 automatic and a 57 automatic and use Type F in both. Anytime I see it I load up on a few cans. F is what the manuals call for.
Thanks to all for the help; the car is back on the road. The trans is leaking pretty badly. I think a reseal or replacement is in order if dad plans to drive the car much. After bleeding the brakes several times I figured out why the brake pedal never firmed up. Turned out the MC push rod had been modified by one of the previous owners. The thing was about 1/4" shorter than the stock piece in my Fairlane. After swapping rods out, dads' car brakes like a totally different vehicle.