OK to use synthetic oil in 1941 Chrysler?

I have a 41 Windsor with only 22K original miles. The engine is completely smooth and the Fluid Drive is
perfect. I was wondering if the old flathead 6 could use something like Mobil 1? Would there be any
detrimental effects to the engine, gaskets, etc? Also, could I use synthetic in the Fluid Drive?

 

The only wild guess I could make is that it should be fine as a
lubricant if you choose the proper weight oil but it might cause older
gaskets to weep and leak. Perhaps a 50/50 mix of synthetic and regular
oil would be best? I'll leave it to the experts.

 

Why would you want to do that?

The advantages of synthetic oils are based on how much and how 'hard'
they are used. You aren't planning on using this engine much or hard.
The only advantage might be the advantage of the synthetic cold start
wear, and I'm not so sure about that.

One article sez that the oil leaks associated with changing from
conventional to synthetic in old engines is related to the detergents
clearing the conventional oil varnish 'clogging' a leak site rather than
hurting the actual seal.

 

I wouldn't. It's not wise to switch an older engine to sythetic.
IMO there would be no advantage anyway.

I would put DuraLube in the engine though.

 

Just on superstition alone, I'd probably avoid the Group IV PAO
synthetics like Mobil 1, Royal Purple, Redline, etc. If you go with the
Group III synthetics like Pennzoil Platinum, Valvoline, or Shell Rotella
T Synthetic (my preference) then you're still dealing with base oils
made from petroleum (although highly refined and modified) instead of
PAO oils made from natural gas. I don't know how much oil your flathead
burns, but mine always tended to sip a bit more oil than modern engines.
The PAOs sometimes cause combustion chamber deposits that other oils
don't in engines that burn oil. That is why Mazda still says "no
synthetics" in the RX-8 rotary engines, which deliberately burn oil to
lubricate the apex seals.