Re: Stuck valves
You might try running synthetic oil in it once and see how it does. Some old engines don't like it and some do. It doesn't get gummy like dino oil. That's the only thing that I'll use on something with a turbo because it doesn't turn to carbon in the super hot turbo when you shut it down and the cooling liquid stops circulating.
Some turbos and superchargers can be damaged by synthetic oil as it has different cooling and surface tension properties among other things. Best to use the oil recommended by the engine manufacturer unless you can afford to live with the results of experimenting.
1995 Valiant 42