Jeep 4.0 oil for summer and winter

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I know the Jeep 4.0 oil topic is pretty beat to death on the Jeep forums but I trust these answers a lot more!
Going to do an oil change on mine within the next few weeks. Right now I have Pennzoil HM 10w40 in it, it was on sale at Walmart and before that it was Pennzoil HM 5w30 for winter. Seems to have helped the leaks. Don't want to run Pennzoil HM again because my local Walmart doesn't stock individual quarts of it in weights besides 5w20/30 and I don't want to pay $8 for the extra quart at an autopart store (takes 6 quarts). Furthermore, if I change the oil now, it likely won't hit 4-5k miles before we get single digit temps starting in December/ January. So I don't think 10w40 would be the best choice. However, with July and August coming, 100 degree temps are possible too. I guess my question is, what would be a good weight that would suit the timeframe of this OCI? The manual says 5w30 from below 0-60F, 10w30 from 10-100+. Mine has 133k miles on it.

Walmart here stocks Maxlife in all the popular weights. Is there such a thing as a 5w40 Maxlife?

Sorry for the diatribe!
 
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My 4.0 has bad lifters. Every cold start it would tick loudly.

My friend with a 4.0 said to use M1 HM and the 10w30 and 5w30 (winter) completely silenced those cold start ticks.

I have M1 HM 10w40 in right now and the ticking has come back to normal. Must be the thick 3.9HTHS.

I'd say give M1 HM a shot. It has been good to me for my 2002 4.0. I would roll with 5w30 and sub a quart for 10w30 or 10w40 and use it year round. That is my plan at least.
 
I've got two '96 4.0 Cherokees and a '98 Grand Cherokee, all with the 4.0 engine. I use 10W-30 in all the engines and I can't really complain about any of them, except the one Cherokee with almost 300K miles has some lifters click at startup and some cold-engine piston slap that goes away after 30 seconds or so.
I use whatever 10W-30 that I have on hand, but lately a lot of Trop-Artic and Peak.
Depending on the year of your 4.0 engine, I'd worry more about a broken piston skirt, a rod going through the block or a cracked 0331 head than I would about the kind of oil being used in a 4.0 Jeep.
 
I don't think they're picky. In my 96' XJ I've run Castrol GTX HM 10w30, MaxLife 10w40, Pennzoil Platinum HM 5w30, Chevron Supreme HM 10w40, Mobil 1 HM 10w30, and currently Napa Conventional 10w30. It runs the same on all of them.

So just pick a quality 10w30 for summer and a 5w30 for winter and you should be fine.

I've heard the 4.0L likes to shear 5w30 so I wouldn't do too long of an OCI, something like 3,000 miles should be fine.

I also have only used Fram Ultra filters and Wix, no issues with either.
 
Would the 10w30 be too thick at around 0 degrees or a little cooler? I guess worst case change it from the 10w30 to 5w30 when the cold temps hit even if it's only been 3k on the 10w.
 
I have had pretty good results with the Xw30 HM oil calming down the small oil weeps.
The 4.0 is just a hot-running engine, so I would stick to synthetic.
 
Pennzoil Ultra Platinum 10w-30 for my 2003 4.0l. Just had an oil analysis: basically still a brand new engine, so I will continue to use it.
 
Thanks for the help everyone! I think I will do a 10w30 (it seems like it'd be fine even if it gets pretty cold here and by December or Jan it'll be ready for an oil change).

From my research, QS Defy (now just known as High Mileage) has higher ZDDP, is that still true? I'll either run that or Maxlife.
 
10W is good to way below zero on the thermometer
smile.gif
 
Thanks guys, I'll just pick whichever 10w30 HM seems to strike my fancy that day since it looks like the Jeep (we named him Carlos) will be happy with any of them.
 
There is nothing wrong with 10w30 down to zero or below in most vehicles, but the Jeep 4.0 is a notoriously fussy cranker at low temps so don't go too thick.

I have generally run 5w30's for the coldest several months of the year and much heavier oils the rest of the time. This last year I used Castrol 0w40 and it worked great, still have it in as a matter of fact since last November.
 
I'll change it out before it gets real cold.

KCJeep, read your thread the other night about oil filters for the 4.0, was the FL400S the winner? How has that worked out despite it being a smaller filter? Could run a Wix 51516 too I suppose.
 
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