Gary,
Had this darn lifter, collapsing all last summer, after I let the van
sit for more than a day. Clack, clack, clack. After about 5 miles it
would pump back up.
Winter came, and I changed oil, and just to be sure the engine turned
over easy, I diluted the oil, substituting one quart of oil with one
quart of MMO.
POOF! No more lifter problems!
I have used this 'miracle" in a can for years, with excellent results.
On a long trip, I will add a pint to my gas to lubricate the valve
stems, and guides. And also it is dynamite for keeping the injectors
clean.
GOOD STUFF!

Later,

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Terry 85 GL