GC or M1 EP for Jeep 4.0

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Brett Miller

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My wife drives a Jeep GC with the venerable 4.0 6 cylinder and 30,000 miles. Right now I am running Pennzoil 10W-30 for my Auto-Rx rinse. I am debating on a long term oil when the rinse phase is complete. My S-10 4.3 seems to love GC so I do keep that in stock. My concern is the supply drying up. Mobil 1 EP 10W-30 also seems like a great choice. Her driving habit is mostly a 5 trip to work which she makes twice a day with a 65 mile trip 1 per month. I would like to extend changes to 6,000 to 7,000 miles with GC or M1 or I could stay with Pennzoil and change every 3,000 to 4,000. What say yee below BITOG'ers? [Patriot] [ February 05, 2005, 06:37 PM: Message edited by: Brett Miller ]
 
GC or M1 EP.....I'd use the most readily available of the two. If both were available at a given location, I'd go with the cheaper of the two.
 
From what I have seen here the 4.0 Jeep engine has not shown great wear #'s with Mobil-1. I done a search and didn't find any Jeep/GC UOA's. So I can't coment on how it does in the 4.0. My best UOA in my 4.0 Jeep came from Torco SR-5 but it's real expensive and not designed to go for extended runs. My next best was regular'ol havoline 10w-30 and a ST filter [I dont know]
 
I'd go with Amsoil ATM 10W30 or M1 0W40 and change the oil twice a year or maybe even once a year and change the filter at 6 months.
 
All of the above are good choices, but I'd throw Amsoil 5w-40 into the mix. I'd use that personally.
 
I'm anticipating that we'll be seeing good UOA from the M1 EP products, but who knows for sure. For now, I'd just say you should consider yourself lucky to be faced with the dilemma of having to choose between known, proven excellence and "almost certainly going to be great" products. [Cheers!]
 
quote:
Originally posted by Brett Miller: My wife drives a Jeep GC with the venerable 4.0 6 cylinder
Actually, the 4.0 jeep engine is a great engine. these engines have been known to easily hit 200,00 miles with virtually no troubles and regular maintence. I have the 4.0 in my 99 XJ and a 2.5L in my 99 TJ. I am running GC and a napa gold in the 2.5L at a 8k OCI and Rotella T-Syn with a Napa Gold filter in my XJ at a 8k OCI. As you have probably seen in the UOA section, these engines typically see very high iron counts. It seems to me that a 40wt can lower the iron and give a pretty good UOA. I will have an 8k UOA on my GC in the 2.5L in about 3-4 months.
 
I have a 1987 Jeep Cherokee with the 4.0 liter engine. When the Jeep hit 100,000 miles, I had been using Mobil conventional 10W30 oil with a regular Fram filter. When I learned more about synthetic oil and its benefits, I switched. I've been using Mobil 1 10W30 with the same type Fram oil filter since then, and my Jeep has 219,000 miles on it. I try to change the oil & filter every 5,000 miles. Hopefully, this information will help you.
 
quote:
When the Jeep hit 100,000 miles, I had been using Mobil conventional 10W30 oil with a regular Fram filter. When I learned more about synthetic oil and its benefits, I switched. I've been using Mobil 1 10W30 with the same type Fram oil filter since then, and my Jeep has 219,000 miles on it. I try to change the oil & filter every 5,000 miles.
These reason above sometimes have me thinking that chosing oils on the basis of a few ppm differences in spectro wear metals is a big waste of time. [Frown]
 
The fact of the matter is the 4.0 could run fine for a very long time on just about any oil, so long as it has oil in it! UOA results seem to suggest that thicker works better in these motors, but again, there are way more stories than can be counted of running it on any old junk 10w30 out to over 200,000 miles. Does that mean the good stuff isn't making a difference? Not necessarily - perhaps on a good diet, 300,000 would be normal, but then again, most of us tire of all the other problems that crop up with hi, hi mileage before we'd ever find out. Based on the info I've seen, I would prefer the GC 0w30 because it is a thicker 30w, and these engines tend to throw lower numbers with those. Of course, the M1 will work fine too...
 
The only troubles with this engine, and this is in engines that are typically 20 years old or older, is blow-by. I've never heard too much of the bottom end on these failing. Naturally a 20 year old engine, that doesn't have 200,000 miles on it, didn't see any daily use and was probably subjected to severe duty/neglect. It's probably on its 5th owner or turned into a semi-dedicated offroad (winter plow/hunting maybe) vehicle. This could lead you to believe that Fe numbers are an indicator of the weak link in this engine. Whether it shows up in 200,000 miles of serious maintenance and consistant daily driver use, who knows? My switching from M1 30 to D1 showed about a 60% reduction in Fe. I tend to lean toward the "less is better" camp on this engine as far as Fe numbers are concerned. My usage (100% synths or pseudo synths) has yielded no increase in fuel economy with thinner oil in this engine. I'm waiting patiently for someone to get a significantly good reduction in Fe with one 30 weight over another. Unless it happens ..there is no reason for me to change my opinion. GC might do a good job ..but if it offers no increase in fuel economy ..it's right up there with D1 for cost...so what do you gain [I dont know] I have one criteria that may be different than others. I'm into extended drains ...so anything that isn't good for the long haul ..need not apply. [Smile]
 
quote:
Originally posted by Eddie: I sold my 95 JGC 4.0L (bought new) with 156,000 trouble free miles using M1 10w30 for the last 153,000 miles. Eddie
Using 10W-30 anything in this engine will give it a long life.What we do here at Bob's is going the extra mile with UOA.Most people don't care whats in the crankcase as long as it runs.Here we go deeper into why and what...it's oil porn [freaknout] .The majority of the UAO's for this engine shows the 40W oil's are perferred.
 
quote:
Originally posted by wn1998:
quote:
Originally posted by Brett Miller: My wife drives a Jeep GC with the venerable 4.0 6 cylinder
Actually, the 4.0 jeep engine is a great engine. these engines have been known to easily hit 200,00 miles with virtually no troubles and regular maintence. I have the 4.0 in my 99 XJ and a 2.5L in my 99 TJ. I am running GC and a napa gold in the 2.5L at a 8k OCI and Rotella T-Syn with a Napa Gold filter in my XJ at a 8k OCI. As you have probably seen in the UOA section, these engines typically see very high iron counts. It seems to me that a 40wt can lower the iron and give a pretty good UOA. I will have an 8k UOA on my GC in the 2.5L in about 3-4 months.
venerable = good......
 
quote:
Originally posted by OdinsRageSS:
quote:
Originally posted by wn1998:
quote:
Originally posted by Brett Miller: My wife drives a Jeep GC with the venerable 4.0 6 cylinder
Actually, the 4.0 jeep engine is a great engine. these engines have been known to easily hit 200,00 miles with virtually no troubles and regular maintence. I have the 4.0 in my 99 XJ and a 2.5L in my 99 TJ. I am running GC and a napa gold in the 2.5L at a 8k OCI and Rotella T-Syn with a Napa Gold filter in my XJ at a 8k OCI. As you have probably seen in the UOA section, these engines typically see very high iron counts. It seems to me that a 40wt can lower the iron and give a pretty good UOA. I will have an 8k UOA on my GC in the 2.5L in about 3-4 months.
venerable = good......
x2 ven·er·a·ble 1. Commanding respect by virtue of age, dignity, character, or position. 2. Worthy of reverence, especially by religious or historical association: venerable relics. 3. Venerable Abbr. Ven. or V. a.Roman Catholic Church. Used as a form of address for a person who has reached the first stage of canonization. b. Used as a form of address for an archdeacon in the Anglican Church or the Episcopal Church. http://dictionary.reference.com/search?q=Venerable
 
Brett - I have a 92 Jeep Comanche with the 4.0 inline 6. It has 135,000+ miles on it and it still runs great and doesn't leak any oil. It was once a daily driver, but now it is my weekend vehicle for trips to Home Depot, hunting, etc. I have never had a UOA performed on it, but I might in the future. It has seen a diet of Havoline 10W30 since I bought it 85,000 miles ago. I change the oil every 3K miles or 3-4 months. I think that this engine is very solid and a strong performer. It sounds like your wife really doesn't get the engine warm enough to get the condensation blown out before she arrives at work. I would consider this a "severe" situation. A synthetic oil is going to have better low temp flow and high heat resitance, but your engine will still have all that condensation in it due to the short trips. It makes sense to me to change it more often and use the dino oil vs. synthetic at 6K to 7K. It sounds like 6K to 7K intervals will be almost one year of driving for your wife. - Just my $0.02 worth.
 
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