The best way to clean up dirty lifters is to purchase a Wix 51734XE oil filter and use a Synthetic oil, that oil filter will catch much smaller particles that lodge themselves into the lifters wich have the tightest clearences inside the IDI engine.
And also that filter will last over 15,000 miles allowing the lubricant extra life due to extra cleaning capability and capacity.
A Win Win when correcting a faulty lifter. If your going to buy oil/filters, just buy the best available, at the end it was much cheaper.
Javier