You would need to be more specific with your question. You are not providing enough information to supply a meaningful answer.
my 1968 9.8 mercury calls for 50:1.
You might want to check local newspapers for a TV repair ad. I can't recommend you one without knowing where you live, but most repair companies do house calls.
what are you asking?
If that is what the engine manufacturer calls for, then yes.
No. "Mercury" dimes (really Liberty dimes, but everyone calls them Mercury dimes) were made from 1916 to 1945. Roosevelt's portrait was put on the dime in 1946, that's why they're called Roosevelt dimes.
Ford calls their 302 cubic inch V8 engine a 5.0 liter
Those aren't headlights, they're considered running lights or parking lights. I believe that mercury calls this a Light Bar.
Ford calls their ( 400 cubic inch V8 engine ) a 6.6 liter
Capacity is 5.3qts., and calls for a 5w-30.
Haynes calls it a "dual load sensing valve," though even Ford personnel can't find anything under that name. It's located under the passenger rear, bolted to the frame with a spring arm attached to the rear axle near the middle of the axle. If you need to find it. . . you will! It leaks like a seive once it breaks (pun intended).
My '97 Mystique 4 cyl calls for 5W-30 oil. Check the owners manual, if you don't have it, google for it. As for brand, I use Pennzoil, but it's all pretty much the same.
Engine 72, assigned to Station I, is the Department's third due engine for all in-town calls. When mutual aid is requested from the surrounding communities.