Nissan Repair: Lose accelaration and noisy tappets, noisy tappets, nissan pathfinder

Question
I have a 1995 Nissan pathfinder 2wd and using a 20/50 engine oil.  For almost 2 months, I notice that when I step on my gas pedal, it has a very slow accelaration and the tappets  are too noisy.  How can I correct this?  

Answer
Alvin,

Change to 5W30 oil like Mobil 1 synthetic or your particular brand.  The tolerances are really tight in a Nissan engine and the oil you have it too thick to lubricate the upper end.  Also, the oil pump is working overtime to push the oil through the galleries.  Thinner oil is the answer.