Buying a ZJ from my work!

TapouT

Well-Known Member
Joined
Oct 5, 2008
Location
Hickory nc
Hey guys I'm planning on buying a 1998 Jeep Grand Cherokee Laredo Special Edition from my work either today or tomorrow. I'm getting it for a great price which is just a little over what we gave him trade in value. It was traded in at my work last week. An old man traded it in and he is the original owner (bought it new). I live in Hickory, NC and the Jeep has been in Morganton, NC all of its life. It has 125,555 original miles on it. Clean title with no accidents. Paint/Body/Interior are all 10/10. It is absolutely immaculate. I could not believe my eyes when I first saw it but I just knew that I had to have it. The seats look like they have hardly been sat in. Paint looks and shines just like it did when new. I will post pics later when I get home.

Here's my issue with it and the reason I made this post. We put it on the lift and noticed a minor oil leak which is fine but every used car traded in at my work gets an oil change and they put 5w30 in EVERYTHING. This Jeep makes the "lifter clapping" noise just as every other Jeep with a 4.0 I've ever owned has. Would it be wise to go to 10w40 oil? It gets pretty hot here during the summer. Oil pressure right now with the 5w30 is 40 psi cold (idle), just a little over 40psi cold (driving), 30psi (warm idle) and 40psi (warm driving). What oil would you all recommend and what is a good filter to run? I just don't believe in running the 5w30 because of how thin it is and this Jeep having the miles it does with an oil leak and the lifter noise. Thanks very much I appreciate the help!
 
I always run rotella 10w30 or 10w40 in my 4.0s
 
my 4.0 with 218,000 miles clatters reguardless if it's 5-30 or 15-40. Oil pressure hot hovers 40 at idle and close to 60 at 2700 rpms. I ran synthetic oils the first 190,000 miles and when I replaced the valve cover gasket, I found the top of the engine looked no better or cleaner thqan any other engine. So been running dino since and it stays clean btween 5,000 mile changes with very little usage loss. I'm running 10/40 dino right now and the solid lifters in my willys flathead are quieter that the valve noise from my 4.0.
 
I've always ran regular Castrol, Mobil 5000 or Valvoline 10-30 or 10-40 in all my 4.0's and I've never had any trouble or noticed any more or less engine noise with either one. For filters, I've always ran the Mopar filters. Think it's M0-090 or something like that. My local WalMart keeps them on the shelf, think they are $6 or $7.
 
x2 on the castrol, mobil 5000 or valvoline 10w-30, i've thought about running rotella since it still has zinc in it to help flat-tappet cams live longer, but haven't made the switch yet.
Oils i will NOT run in a 4.0 are paraffin based(any Pennzoil or Quaker State) and any 5w-30 or thinner.
For filters, i like Wix filters, which are also NAPA or carquest, depending on which color paint you like on the filter
 
These jeeps call for 10w30 from the factory, says so under the hood somewhere. Mine just rolled over 200k, and I've always ran 10w30 in it. Yes, the lifters are noisy when you first start it up, but after 5min or so, it goes away. I've thought about bumping it up to 10w40 or 15w40, but it doesn't leak, and doesn't use much oil between changes, so I'm trying to hold out for as long as possible before going to the thicker oil.

If I were you, I'd run the 5w30 for about 1000 miles, and add a bottle of CD2. It's an oil additive to help quiet those noisy lifters, and it does a really good job IMO. Change the oil after 1000 miles for some 10w30 and drive it.
 
Thanks for all the help fellas! I think I'm going to go with Castrol High Mileage 10w40 and a Mopar filter. The noise does get quieter when warm but is still there and still noticable so hopefully this will help.
 
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