Jeep Enthusiast Forums banner

Oil recommendation for 4.0

1K views 11 replies 8 participants last post by  1998XJLtd 
#1 ·
My 4.0 was nice and quiet on start up and run. I tried Amsoil Race this year because I use it in my bike and it's great. PLus a nap gold filter because I had it laying around. But now in the 4.0 I get the lifter clack on start up. What oil should I run to quiet this down? I do not remember what I had in before unfortunately. Pretty sure it was Pennzoil. I know I used a K&N oil filter.
 
#7 ·
I was thinking the same thing. I am not sure how heavy of an oil a 4.0L can take. I did have a Ford Contour with the 4 cylinder or was it my SVT. I used a 20W-50 in it, Mobil 1. It clattered a bunch. I didn't run that oil long. Ran OK after that. (not a bash on Mobil 1).

I like to use Shell Rotella. The do make 10W-30 and 10W40. I like to use a bit higher zinc levels. I do use a NAPA oil filter. I am running Rotella T6 presently. Its a synthetic. Still, nothing wrong with conventional oils.

Also, you might lose a few MPGs with a heavier oil.
 
#9 ·
Be careful about using oil with "lots and lots of zinc" as this can easily lead to catalytic converter damage. Yes, flat tappet engines like the 4.0L need more ZDDP than more modern designs to prevent excessive valvetrain wear, but you can quickly reach a point of having too much of a good thing which can cause problems elsewhere.

Unless your bearings and oil pump are worn to where you can't keep pressure in spec, there's not much point in running oil heavier than 10w30 in these engines.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top