Nissan Repair: 93 maxima knocking (sometimes), feeler gauge, cam followers

Question
93 maxima with ve30de engine has knocking or tapping sound in rear valve cover but it doesnt knock all the time mostly after wamed up but still phases in and out starts and runs great,no engine code lights on its a spare vehicle so its not driven alot have put engine @ injector cleaner in but doesnt help if anything made it worst any help appreciated

Answer
I would go with a change of the oil to a 10W30 or 10W40 weight engine oil.  I like Mobil 1 but with the age of your car it would leak at every seal.  Mobil 1 is great for getting things unstuck in an engine but with age Mobil 1 will find a leak path.  So, I would go with whatever brand you like and change it.  If it still makes a tapping sound you should remove the valve cover and inspect the cam followers for excessive play.  I do not have a book on your year.  But, the ve30de is basically the same engine design.  So, the lifters have provision for adjustment.  You will notice a nut and a small threaded portion at the end of each arm.  You will need a feeler gauge to make adjustments to the specifications called out in the book for cold or hot lash.  If your car does not have provision for adjustment you will need to buy the lash dampners that are within the arms.  It is not too difficult to change them out if you have the kind that do not adjust.  SO, those are your options.  On the use of injector cleaner I would just go with Chevron or another quality brand of Super unleaded.