Synthetic for '01 Cherokee

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May 19, 2004
Central NY
I am contemplating oil choices for my "new" '01 Cherokee with the 4.0. I have done quite a bit of reading here and it seems the UOAs are a little better for an xw-40 vs. an xw-30. I am an Amsoil user and I was just getting ready to dump some 10w-30 ATM in there with an SDF15, but now I am having second thoughts. I live in a part of western NY where winter lows of -15°F occur almost every year, and morning cold start temperatures of -5°F to 5°F are relatively common. I have been running the 5w-30 ASL in my wife's subaru with excellent results at 7500 mile OCI. I would like to find an xw-40 for the Jeep that I could run all year, if that is both possible and wise. I am not going to use crazy OCIs, so changing for the seasons isn't a problem. Wear, cleanliness, and fuel economy are my priorities in that order. I will be driving about 25k per year.
There are a number of good reports (via analysis) of synthetic oil for the 242-6. Our 2001 is being driven an average of 25k annually, and our goals are the same as yours. Our analysis reports have been excellent, and a near future one will feature a 10W-30 synthetic. Were yours mine I would purchase a couple of gallons of FUEL POWER (more than pays for itself in our experience), and treat the vehicle to an ARX regimen prior to use of synthetic. I use REDLINE products in the power steering and rear end, as well as SCHAEFFERS in the transmission (and addition of coolers and auxilary filters for both). Dallas is a tremendously hot place -- and these Jeeps feature rather small radiators (why I also am pleased with SCHAEEFERS "Clean & Cool" after a careful distilled water flush with Prestone "drive-it-around" cleaner) -- and for oil I am not now convinced that 10W-40 is necessary if the oil is of very good quality. I have made a number of posts in re this Jeep and the use of the above products which you may find beneficial. I will also highly recommend the services of Terry Dyson of DYSON ANALYSIS (member #9) as your guide in economy, reliability and longevity goals. I have been under his guidance for more than 30k miles on our Cherokee (42k thru 74k at present) and believe that there is not a substitute for professional advice. Good luck. [ May 21, 2004, 10:30 PM: Message edited by: TheTanSedan ]
Amsoil 10w30 is almost a 40 weight......and will probably be a 40 weight after awhile.........depending on how long you plan to run it. The amsoil may work very well. [Smile]
Thanks for the replies. I am just nearing the end of an auto-rx cleaning cycle using Pennzoil 10w-30. I think this oil is a little too thin for this engine at 10.5 cSt, so I am going to rinse with 10w-40. Whatever oil I choose will go in after that. The dealer did a fuel injection cleaning trying to clear up a cold start miss (I think a PCM reprogram will actually fix the problem per TSB 18-010-01), but I am still getting a little knocking climbing a nearby hill. The OTC products seem rather ineffective. I may give the fuel power a try. The subaru likes to carbon up too, so I may try it in that as well. I really like the ATM in the subaru, the engine runs quieter than either Pennzoil 10w-30 or Mobil 1 10w-30, probably just the higher viscosity. I am not opposed to running it in the jeep, I just want to make the right decision out of the gate. How would oils such as Mobil 1 0w-40, Amsoil 5w-40, and Delvac 1 compare to the ATM? Keeping in mind running it year round with -15°F cold starts.
At 25k a year ...your starting frequency should be very low. Unless you live in the vehicle all day long're on the highway for the majority of your driving. That is, your "cold start" frequency has to be very low. You can't accumulate 25k otherwise in a year's time least one would think. I don't think "cold start" should be your primary concern in choosing an oil. That all being said... I've had my best results with Delvac 1 ..but I'm into XOCI and have a larger sump. My son also runs Delvac 1 in his 00 Cherokee ..but he's into a by-annual OCI. We don't see quite the cold that you do typically. We're usually on the plus side of zero ..but I think close enough to say that a 5w-40 (Delvac 1) would function well in your 4.0. I also think that you could easily do well with a 12.5k OCI using it. IMHO ..given the mileage you accumulate AND the frequency that you're looking for with OCI ..I doubt that I'd go to the expense of using a synthetic. You're going to be doing a minimum of 3 oil changes a year (@7500 miles) and this would allow you to be very "climate selective" on the weight that you choose (as you eluded to). You also do so much maintenance ...that the use of various other agents (ARX, FP, LC and the rest) are not difficult to "fit in" to your routine. That is, any detractors for any dino oil are easily neutralized ..and at virtually no increase in costs. I think that if I were faced with your situation ..and I felt the way that you do about OCI ..I would have a "winter" OCI and two for the rest of the year. That is, a 0w-30 or 5w-30 for that brief period ..and make it temperature dependant (time weighted) ..and then divide the remaining two OCIs equally for the remainder of the year (something like 5k + 10k + 10k). In my experience this engine responds better to the x-40 weight oil but admittedly ..with XOCI's hard to compile too much data (with over 10k OCI) on too many different oil/OCI combos.
Non-synthetic is not an option. My experience has shown that the cold start, cleanliness, and my somewhat extended OCIs are well worth the money. I was into my wife's subaru for the head gaskets at 120k miles after 50k of Mobil 1 and the thing was amazing, no sludge, varnish, or deposits of any kind that I could see. I just couldn't stand the horrific clattering noises and water-like appearance of the oil when I drained it, so I started using Amsoil. She drives 30k a year. I drive about 110 miles round trip half of the time to work, as I carpool with a guy that lives nearby and works at the same company. Operating temp lubrication is obviously very important, but I don't think I can neglect cold start properties. Freezing temperatures here start in November and end in April. I can't see myself running oil beyond 7500 without analysis. I will most likely stick with the SDF15, as it is a great filter at preferred customer cost. How does the cold cranking of say the AFL compare with ASL, which I am happy with in the subaru? They are rated at different temperatures on the Amsoil website. [Bang Head] The AFL doesn't list a borderline pumping temperature. Is the ASL enough better than the AFL to justify using it in the winter?
The CCS viscosities of the Amsoil 5w-30 and 5w-40 are roughly the same - both are approx 5000 Cp @ -30C/-22F. If you want a thicker oil for the summer, the new Amsoil 5w-40 would be the way to go. The 5w-40 also meets a number of passenger car diesel specifications, so the detergency should be even better than ASL. The additive chemistry in the 5w-40 is actually very similar to the 10w-40 and Series 3000, 5w-30 formulations.... Tooslick
I ran my 96 4L Jeep engine on Mobil 1 10w30 for 162,000 trouble free miles and sold it to my son-in-law who now has over 175,000 miles on it. 5,000 mile oil/filter changes was the solution.
I just tried SuperTech "full synthetic" 10W-30 in my ZJ problems so far, planning on running for 4-5K w/it. I used to run M1 full synthetic, but I am probably going to start using a GIII oil due to cost and a develping rear main seal leak (no, I don't think it was the M1 that caused the seal leak, it is a VERY common problem on the 4.0L...and it does not even really leak much at all..[no oil consumption for 3k miles indicated on dip stick]) I have run just about everything in the 4,0L and honestly I never see much of a difference in performance. I also run the K&N air filter of death [Smile] on it. [ May 22, 2004, 06:59 PM: Message edited by: OiledMustangGT ]
Well, I changed my mind, for now at least. My wife's subaru at ~160k miles is starting to use a bit more ATM than I care for. It's really begging for a 40 weight IMHO. I have a case and a half of the ATM and a case of the AFL. I am at the end of the Auto-RX rinse cycle in the Jeep. I am going to change the oil in the Jeep tomorrow and use ATM, and the subaru will get AFL at it's next change. I will run two short OCIs in the Jeep with the ATM to "get it used to" the Amsoil (and to use it up), then go to AFL year round. I am hoping to do 10k OCI with 5k filter changes, no analysis.
I just sent off a 10500 mile sample to Blackstone from my Jeep. I changed the filter halfway through and was using the 5W30 ASL. This should give a good snapshot of how this oil will hold up in a 242.
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