I'm new to Jeeps, just bought my first one. 1999 Grand Cherokee with the 4.0 inline 6 with 112k. I have no idea what oil is in it currently. I found out my stash of filters I bought for the 02 caravan will also fit the Jeep so I'll be using PureOne filters. I bought some PYB to run for the first OCI since I've read on here about its excellent cleaning abilities. I have on hand several 5qt jugs of Maxlife I was planning to run after that. I was reading on Jeepforum.com someone recommended Rotella T5, saying its better for the "older technology" of the 4.0 engine. So that has me wondering, do I need something like T5, or perhaps QS Defy, for higher zddp? What do you think?
Oil recommendations for 1999 Jeep Grand Cherokee
- Thread starter Jay1981
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I've got two '96 Jeeps and a '98 Jeep, all with the 4.0/six. It is my opinion that you can run about any brand in your Jeep, especially since the engine has long been broke in. I run TropArtic in mine, but that is only because the Orscheln stores (I see that there are none in your state) consistently have the sub-$2/quart oil sales. I think the Defy would also be a good oil.
The older 4.0 engine is not picky on oil. I'm more picky on the oil filter than I am of the oil.
The older 4.0 engine is not picky on oil. I'm more picky on the oil filter than I am of the oil.
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My wife had a 95 Grand Cherokee with the same engine. It was happy on a steady diet of M1 10w-30, and later M1 HM 10w-30. She bought it new and we kept it to almost 200k miles. The HM version is higher in zinc than the standard M1 or M1 EP. Previous poster is correct, that engine is not picky about oil.
That engine is a fine engine as long as it is taken care of. I have had one for 20 years with the same engine and it has been great. I use decent filters such as Purolator and mine is not picky about oil. It gets all types and usually in 5w30 or 10w30. I put 10w40 in it last summer because I got the oil for 99 cents a quart and could not resist the deal. I change my oil every 4k miles or so. You can use the Rotella if you want to. The jeep engine is a good one. Hope yours serves you well like mine is.
They're saying to run 10W-30 Above 0* F.
Hello, 'Sis' had 2(a 1988 and a 1999) 4.0L Cherokees spanning 15 years+. I serviced them with the recommended 5W-30. I'd show you pics of a clean valve train if I knew how to attach them. Kira
owners manual says 10w30 above 0* and 5w30 below 60* but "modern" 5w30 is generally considered a good year-round oil, especially here in Michigan. If I went with what the owners manual says I'll end up changing it weekly if not daily lol.
PYB is fine for your 4.0L. No need for an oil beyond SN levels of ZDDP. The Maxlife is nice too, especially if your rear main has a drip or two.
My Jeep gets what's cheap. I have about a year's worth of Peak 10w40.
Some (like me) are using 5W40 (T6). But 10W30 is fine also. Its a tractor engine as some have called it.
The '98 has 5W30 Maxilfe synthetic in it now, when it warms up it'll get PYB 10W40, running strong at 219K.
I have found PYB to run the quietest in my 4.0L. I have done a UOA on the 5w30 and the 10w30. The 10w30 showed pretty low iron wear compared to the average.
Like they said it'll run on anything.
Top picks in PCMO's for smooth quiet running would be PYB and Defy in that order. I'd be happy with just those two the rest of my Jeep's days in fact.
Rotella and Maxlife have also consistently posted stellar UOA's in the 4.0 but both of them are noisier for me anyway.
I suspect QSGB would be a fantastic match for the 4.0 as well but I haven't UOA'd it yet. When I get through my stash its back to PYB for me.
Top picks in PCMO's for smooth quiet running would be PYB and Defy in that order. I'd be happy with just those two the rest of my Jeep's days in fact.
Rotella and Maxlife have also consistently posted stellar UOA's in the 4.0 but both of them are noisier for me anyway.
I suspect QSGB would be a fantastic match for the 4.0 as well but I haven't UOA'd it yet. When I get through my stash its back to PYB for me.
Those aren't picky. I'd get whichever 5w30 is on sale at the time of your next oil change. If it leaks or burns a bit of oil, try a 5w30 HM. You have a lot of good choices in either category. You don't need high ZDDP levels in that motor.
If it is to be used for towing and heavy-duty work like off-roading, I might be inclined to look for a 5w40...but today's 5w30s are quite stout.
If it is to be used for towing and heavy-duty work like off-roading, I might be inclined to look for a 5w40...but today's 5w30s are quite stout.
Originally Posted By: jeepman3071
I have found PYB to run the quietest in my 4.0L. I have done a UOA on the 5w30 and the 10w30. The 10w30 showed pretty low iron wear compared to the average.
And it means nothing without establishing trends for your particular engine.
Used oil analysis aren't meant for nor are they an accurate way to determine wear. So your high or low iron readings don't mean anything.
A used oil analysis is meant to establish trends which then can be used as a tool for diagnosis if an anomaly presents itself and to test the condition of the oil.
Read Doug Hillary's posts. He's an expert if there ever was one. You'll learn much.
I have found PYB to run the quietest in my 4.0L. I have done a UOA on the 5w30 and the 10w30. The 10w30 showed pretty low iron wear compared to the average.
And it means nothing without establishing trends for your particular engine.
Used oil analysis aren't meant for nor are they an accurate way to determine wear. So your high or low iron readings don't mean anything.
A used oil analysis is meant to establish trends which then can be used as a tool for diagnosis if an anomaly presents itself and to test the condition of the oil.
Read Doug Hillary's posts. He's an expert if there ever was one. You'll learn much.
I switched from Chevron Supreme (Costco special) to Rotella T5 over the past two OCIs and haven't noticed any noticeable difference.
I'll be switching back/to Chevron/PYB from now on for availability and value, depending on which I can get at the moment for better price.
I'll be switching back/to Chevron/PYB from now on for availability and value, depending on which I can get at the moment for better price.
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