Originally Posted by DJRoy
1950, 235 engine will synthetic oil damage the engine or help cleaning it out?

Synthetic oil won't damage your engine. Depending upon the additive pack in the oil, synthetic oil may or may not clean your engine better than the mineral oil you're using now. If you're not having extended oil change intervals, you probably won't get the benefit of synthetic oil.

Mobil 1 video - Is Synthetic Motor Oil Good for Everyday Cars?

See Selection of the Right Motor Oil for the Corvair and other Engines

Older, flat tappet engines should use Heavy Duty Engine Oil and I use Rotella T 10W-30 in my slant six.

Engines depend upon oil FLOW for lubrication and pressure is related to flow and viscosity. Using and oil that is too viscous just means that more oil gets recirculated back to the sump by the relief valve.

Rods & Relics - Fort Erie / Collector Car Tech