help me choose a new oil

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I am wanting to try a new oil in my Jeep 4.0l
I started with Mobil 1 5w30, I felt it wasn't robust enough for the jeep, so I then went to amsoil 5w30 series 2000 heavy duty engine oil. I really was fairly pleased with how this oil performed. I just became tired of the constant orders to amsoil (yes I know I'm lazy). I then switched to Rotella T 5w-40, I haven't been real pleased with this oil, I have more consumption with the rotella and mileage has dropped Amsoil was zero consumption in 8000 miles as opposed to the rotella's 1 quart. Also Mileage is down 1-2 mpg.

I am now looking at going with either Mobil 1 0w-40, or Mobil 1 10w30 High Mileage. They both seem to be a poa from oil analysis, not for sure though. They are both comparable in zddp and calcium and moly and the such also, so anyone have experiences with both ?

Also a couple of other questions I have heard contradicting statements that Mobil 1 Turbo Diesel Truck 5w-40 and Mobil 1 Truck and SUV 5w40 are the same formulations just different bottles and that they are different which is true ? Then of course the last question. How do you read oil viscosity on oil analysis, they say The mobil 10w30 high mileage is a heavy 30 and the 0w-40 is a light weight 40, how do you tell ?
 
The best used oil analysis were have here on BITOG seen on a Jeep 4.0 have been with good old 10w30 oils.

My uncle runs 5w30 in his Jeep during the winter and 10w30 the rest of the year. And he uses the 4x4 like a jeep should be used throughout the year. He just passed 100k on his engine. (he has had to replace the clutch last month)

If you want to run a syn, try Pennzoil Platinum 10w30 and see how it performs for you.

Take care, Bill
 
i would to what billinutah says but from what i read here, you could just upgrade all the filters if you don't run them already and stay with the amsoil 10w30 or a 10w-40 for a longer OCI so you don't have to order amsoil but a couple times a year.
 
Originally Posted By: Dupree
robust enough for the jeep


LOL! "define" robust? How about 40W70 or bucket of wheel bearing grease?

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b 40-70 "robust" bearing grease haha, good one....dont all chryslers go with 5-20 now?
 
Originally Posted By: aaxb970
Stick with what the engine is speced for. The engineers who built the engine know what will grade will work best.


+1. Their knowledge > your feelings of how robust the oil "feels".
 
This is flat tappet engine for those finding humor of my choice of wording or even the desire for a robust oil. I find lower wear using heavy duty engine oils through uoa.
I like the Rotella I am using it in my Slant six flt Tappet. I just am not impressed with consumption and MPG in the jeep. My main choice is between the two mobil oils. Not looking for a golly gee wilikers formula 2960 billy bob oil is the best and what you should be using. Just would appreciate experienced users of mobil high mileage 10w30 and 0w-40 to pitch in there experiences. Thanks everyone
 
a slant six should be run all the time with regular 5w30 conventional. if u wish to baby her with something more robust, then look no further than any cheap semi synthetic 5w30, or to really pamper her with a verrry robust oil, the SuperTech synthetic 5w30 will do the job.

say after me, slowly... oil is never too thin, oil is just too thick.

if consumption is going up, and mileage is going down, doesn't that say something? mileage down, means more friction. more friction = more heat and more wear. why would u want that?
 
Originally Posted By: scoobie
a slant six should be run all the time with regular 5w30 conventional. if u wish to baby her with something more robust, then look no further than any cheap semi synthetic 5w30, or to really pamper her with a verrry robust oil, the SuperTech synthetic 5w30 will do the job.


slant six gets rotella T 5w-40 I am happy with the slant it does well with this oil, I have no desire to change the slant, I was just using it as a reference. I used the same oil in the Jeep 4.0l and THAT is the vehicle with consumption and reduced MPG issue.

Originally Posted By: scoobie

if consumption is going up, and mileage is going down, doesn't that say something? mileage down, means more friction. more friction = more heat and more wear. why would u want that?


uh ok are you inferring that the heavier oil is producing more wear to the motor because the used oil analysis seem to disagree with you on this motor. I ran 5w30 mobil in her for a while.......
 
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UOA could be a lab error. they could have mixed up the samples.
I cannot believe that a gasoline engine needs anything heavier than a 5w30, unless crossing Sahara desert, towing a mobile home, at constant 75 mph from dawn to dusk.
 
There are many used oil analysis on BITOG for the Jeep 4.0L engine discussed here. The oils that do the best in metallic wear numbers are generally not the 5w30 oils that the owners manual specifies.

I have experience with Mobil 1 Extended Performance 10w30 in my Miata (owners manual says 5W30). Mobil 1 Extended Performance 10w30 gave excellent UOA results with wear numbers in the single digits at 5000 mi.
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10w-30 oils do seem to produce decent numbers in many of these engines. Mine appeared to do the best on 5w-40 Delvac 1. Much better than other XOM products in the 30 grade.

10w-30 always had a PREFERRED in the manuals of both my 2.5 and 4.0 (02/99MY)
 
Originally Posted By: scoobie
a slant six should be run all the time with regular 5w30 conventional. if u wish to baby her with something more robust, then look no further than any cheap semi synthetic 5w30, or to really pamper her with a verrry robust oil, the SuperTech synthetic 5w30 will do the job.


ST syn is robust? It shows decent wear numbers for 5K changes, but otherwise it's a pretty "bland" oil (and I've been running ST for many years).

Originally Posted By: scoobie
say after me, slowly... oil is never too thin, oil is just too thick.


That's not true.
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Originally Posted By: scoobie
if consumption is going up, and mileage is going down, doesn't that say something? mileage down, means more friction. more friction = more heat and more wear. why would u want that?


Mileage down, doesn't mean more friction. Oil has more functions in an engine than supplying bearings with lubrication.

I run 5w30 conventional in my Jeeps in winter and SAE30 or 10/15W40 in spring/summer/fall.
 
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