My recently purchased 1983 El Camino, which has relatively low miles and was stored for two years. It has one valve that goes tick-tick and my mechanic, who serviced many other things suggested I drive it for a while and try a combination of 20-50 and 10-40 on my next oil change. Any suggestions of something to add before I change oil, in hopes of getting lubrication to the offending valve?
Thanks,
Eric

...Any suggestions of something to add before I change oil, in hopes of getting lubrication to the offending valve?
I've been successful unsticking lifters using Marvel Mystery Oil. That is a listed use for the stuff. Just dump a quart in the oil when it's time to add oil. It's a last ditch effort for stuck lifters and rings I try before breaking out the wrenches. In my MCSS, I use one quart between oil changes to replace oil I've gone through. At oil changes I put in four quarts oil and one quart Marvel Mystery Oil.

Be carefull because it dissolves all of that old crud built up in your engine. After your initial quart you should change the oil and filter within 500 miles.

I have also used Marvel before with some success.

A can of STP Oil treatment has helped me in the past. Had an Ex Taxi with 240,000 miles that sounded like a diesel idling, and this quieted things right down.

I third MMO. I swear by that stuff, great for just about anything. Of course it has been a whole week since I've used it. :)

Like the others say, Marvel Mystery Oil is good stuff. But, like Ernie said, it should be a last ditch effort. It is strong stuff and too much will cause worse problems than you already have.

Before using MM oil, I would change the oil and use one quart of Risolene in place of one quart of oil. My truck came from the factory with a 305 engine. Somewhere along the line one of the lifters developed the same problem you describe. I used Risolene at oil changes everytime the problem returned. It always worked. The lifter lasted until I changed out the engine for a crate 350. Risolene comes in a bright yellow quart bottle shaped just like a quart of motor oil and can be found at Advance Auto Parts and Autozone among others.

If that fails, you could go with the last ditch effort, Marvel Mystery Oil.