Well thanks everyone! This is what I was looking for, honest real world users.
Got it, 5w-30, 10w-30, 15w-40 all good, find what my engine likes (lifter tick wise) and quit overthinking and quit listening to the "ADD ZINC OR IT"LL ESPLODE HOLMES!!!" guys. LOL.
I use the Fram XG8A 5" filter and change it every oil change. I've been told I can change it every other oil change no problem. With the engine so clean internally, the oil in there now, PYB dino still clean and fairly transparent even so close to 3000miles, I may do that. I'm going to send out a UOA just to get a idea of how the engine looks in that respect.
Going to take Camprunners advice and run some Dello 10W-30 this next change and see how the engine likes that.
I'm sold on the Baldwin Filter, B7311-MPG Heavy Duty 7" Oil Filter, Going with that next oil filter change, synthetic oil and extend the change out past 5000miles(only because it's a laziness thing, I don't have to crawl under so much).
Again, thanks much!
Oil recomendation - Jeep Grand Cherokee 4.0L
- Thread starter RJCannon
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I have a 2003 4.0L Jeep, with the flat tappets as your engine does. It was under the 7 year warranty so I had the dealer change the oil for the first 7 years. Oil change every 6 months. I never had a warranty claim on anything. They used Pennzoil yellow bottle 10w-30 conventional. After warranty I switched over to Pennzoil Ultra Platinum 10w-30. So about half of its life on one oil and half on the other. Now I change the oil myself once a year. Had a Blackstone oil analysis done; no issues. Temperature ranges from -10 when it is parked outside in the winter to some days in the low 90's in the summer.
I am guessing that your 4.0L probably specified SH oil, my 4.0L specification was SL. I don't know what the zinc specification was for those oils but I know someone on this site does. Now with SN oils I think the zinc spec is 800. That would be interesting to know. Exactly how much of a zinc reduction has there been? By the way, the Chrysler specification for the 2003 4.0L was to meet MS 6395. The Pennzoil I am using now, the SN variety, meets MS 6395, so I assume the 4.0L will be fine with it. Good luck on hitting your 300,000 mile mark!
Flow is over rated and somewhat of a red herring ... Positive displacement pumps pump the same as long as it's liquid and can get up the suction tube. OTOH, motors over 150,000 have opened up the bearing clearances some, so you want enough viscosity to keep a nice film in there.
Me, I'd run Maxlife red bottle (semi-syn) 10W-30 or 10W-40. Good seal conditioners. Good base oils and stout add pak. Other choices are HDEO's like Delo/delvac/Rotella.
With clean motor, let the filter go to second change.
Biggest issue is keep it full. Don't let it overheat. Otherwise it's a stout motor that will run a long time 
Wow OP you went from one extreme to another.
On my third Jeep I-6 and have long thought 15w40 is ridiculous overkill. I think you reached the same conclusion.
It's not really start up wear, warm up wear is the period when engine wear is higher. Don't buy into this nano-second of start up flow nonsense, it's pointless unless you are in the Arctic.
Regardless of all the thin oil posts on here, it is indisputable that PART of an oil's engine protection is indeed viscosity. The Jeep 4.0 does need a bit more viscosity than a much more modern engine. The 4.0 pistons in particular will not respond well to a 20 grade oil, if you were to do a UOA I'd bet your aluminum numbers would be 4 to 5 times the universal averages.
Fortunately it's a Jeep 4.0 and it will run well on most anything. Optimum for the Jeep 4.0 it has been my long time position a thick 30 grade or a light for grade 40 grade fall right where the 4.0 does best.
Fwiw, when I was researching oil specs on my 1999 LS1 and 2002 4.6L when I first got there (SJ/SL), I recall the Zinc levels on those at the 1,100 ppm range. One of the reasons I'm using M1 0w-40 in my 1999. Then again, today's SN oils can have other things besides ZDDP to give you adequate Zinc. That can be through more efficient forms of Zinc (less does more) or other anti-wear agents, some may not even show up on the VOA.
Old Bitog thread
Originally Posted By: KCJeep
Wow OP you went from one extreme to another.
On my third Jeep I-6 and have long thought 15w40 is ridiculous overkill. I think you reached the same conclusion.
It's not really start up wear, warm up wear is the period when engine wear is higher. Don't buy into this nano-second of start up flow nonsense, it's pointless unless you are in the Arctic.
Regardless of all the thin oil posts on here, it is indisputable that PART of an oil's engine protection is indeed viscosity. The Jeep 4.0 does need a bit more viscosity than a much more modern engine. The 4.0 pistons in particular will not respond well to a 20 grade oil, if you were to do a UOA I'd bet your aluminum numbers would be 4 to 5 times the universal averages.
Fortunately it's a Jeep 4.0 and it will run well on most anything. Optimum for the Jeep 4.0 it has been my long time position a thick 30 grade or a light for grade 40 grade fall right where the 4.0 does best.
Nick1994
$100 site donor 2023
I used to worry and research what oil to use and what grade.
I've come to realize that for the most part, oil is oil. The Napa Conventional I've got in my Jeep was $1 per quart and I bought 24 quarts.
BrocLuno and KCJeep above know what they are talking about and are worth listening to.
I would run a 10W30 oil, either in conventional form like GTX and PYB, or in semi-synthetic form such as Castrol Magnatec and Valvoline MaxLife.
Right at the thick end of the 10W30 scale, you should find some HDEOs like Rotella and Delo, as another option for you.
Originally Posted By: Nick1994
I've come to realize that for the most part, oil is oil.
I use m1 0w30 ESP
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