I was just wondering if it made a difference in mpg. In my ranger, i use mobil 1 in the engine and amsoil in the tranny, t-case and rear diff. I have a bunch of mods as well, but when the truck was new, I was getting around 18 mixed driving. After mods and synthetics I'm getting 22 mpg, also the engine got broken in some. Has anybody gotten better mpg by using synthetics in the whole drivetrain, or doesn't it help on a kj ?

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06 jeep liberty 4x4 65th aniver edition

04 ranger xlt sc 4x4, 4.0 sohc, 5-speed, gibson dual sport, cai, udp, bama tune, BFG's, and tru-trac

07 redfire mustang GT, 4.6 3V, 5-speed

I use all Amsoil products front to rear but I do not keep that close an eye on mileage any more. I get what I get and worrying about it isn't going to make it any better so why bother.

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99 TJ
71 C101
04 KJ
03 SFA KJ Sport
LOST JEEPS So-Cal

I didn't go all synthetic for better mpg, it seemed to be just a side benifit after doing so.

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06 jeep liberty 4x4 65th aniver edition

04 ranger xlt sc 4x4, 4.0 sohc, 5-speed, gibson dual sport, cai, udp, bama tune, BFG's, and tru-trac

07 redfire mustang GT, 4.6 3V, 5-speed

Don't get me wrong, that is one good reason to switch as it has been proven to help with mileage. The first thing I noticed is my Jeeps just seem smoother overall. I will admit to noticing a few more miles on the OD before my fuel light comes on but I have not figured out the actual mileage. Trying to keep on top of it on 3 vehicles would be a pitb and our driving is fairly evenly distributed over those 3 vehicles.
I even switched my lawn mower to Amsoil and was amazed at how much smoother it ran and how easy it starts now. I bet I'm even getting better mileage out of it!

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99 TJ
71 C101
04 KJ
03 SFA KJ Sport
LOST JEEPS So-Cal

Wouldn't that be gas acreage? Dunno. I have used synthetic fluids front to back in vehicles for years and I feel this is the best way to treat a vehicle. My reason for doing so isn't economy (well, not directly), but because I live in a cold climate. This is where synthetic fluids really shine. WAY better for the mechanical parts IMHO.
When I was a kid my dad had to wake my brother and I up early a few times in very cold weather to help push the old Rambler. Not because it wouldn't start, but because the axles were so frozen the engine couldn't move the car. What a joy when you're 12: get out of a warm bed, run out into -35 cold and push a darn car...

It helps with mileage, all the mechanicals last longer and can take considerably more abuse. I even use synthetics in my chainsaw, 15 years old and still going strong on the original carb and piston/rings. I think I've changed the spark plug once, never seems to foul like it used to on the dino oils. A use Amsoil on eveything I own, the greases are great also. Haven't replaced a bearing, even in my boat trailer since I started using syn grease. 288,000 miles on the bearings in my truck.

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No one knows as much as all of us.

Ohh, wow. Ive never heard of the axle oil freezing!!

I run SYN oils in everything also. i tow and off road alot so I feel thats the least I can do for it.. Ill be using Amsoil in the tranny when that time comes.. I want the best I can get for it..

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LOST KJ'S
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Current Jeep: 2004 Jeep Liberty
-Atlantic Blue
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Likely a combination of wheel bearings frozen solid and diff lube so cold that the assembly would not turn. Synthetic grease makes a dramatic difference in this case. What surprises me is the number of folks who live in very cold climates who do NOT use synthetic lubes. The difference is like night and day. My brother is a mechanic and he won't put anything but Amsoil in his vehicles. I don't know much about specific brands, although with JJsKJ's help, I am learning . Whatever brand of full synthetic (not blended) a person chooses, it is a dramatic step up in performance from the other stuff.

Hey Snowsport,
Man, -35, now that is cold.....I live in the Denver area and we do see a good cold snap a couple of or a few times a year. I am just waiting for the 4000 mile mark to put in full syn in the engine for better cold weather start up.
QUESTION- I have the part time 4wd transfer case. So in theory, do to its limited use, it should not need as often of a drain as the full time, correct? Some people claim that when they drain their transfer cases the fluid is nasty. So I am assuming that this is from full time transfer cases, right? I know it uses atf4 from mopar, but am confused if it will need a flush very often do to its limited use.(Sorry for the hijack, the question just popped in my head.)
Thanks,
Steve

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'06 3.7 sport 6 speed (long live manual tranny's)
tinted windows, cruise, midnight blue
Mopar roof rack
Royal Purple Synchromax in tranny
Royal Purple Maxgear in pumpkins
Full mopar skids, front diff collar
Future mods: Rock rails, B.F. Goodrich all terains. (In my dreams: Frankenlift)

That's a dang good question. I don't know the answer, but what you say makes sense. I'm just following the recommended servicing for my Selec-Trak (full-time). I use the full-time option just about all winter. Maybe someone else will be able to field this question better.

At a minimum you should follow the mfg's interval for the transfer case. If you run a good quality synthetic ATF, like Amsoils that beats ATF+4 specs, in the case it can be changed less often for sure.

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99 TJ
71 C101
04 KJ
03 SFA KJ Sport
LOST JEEPS So-Cal

I agree, synthetic oil is great for really cold temps. I use Mobile 1 myself. Having lived even further north then I do now, Yellowknife, NWT, Canada. Expirence(d) -40 and worse at times and , touch wood so far, have not had problems w/ starts, ect. I have to leave her unplugged during day for 9 plus hrs at sub -30 while at work in a wide open parking lot w/ a wicked windchill blasting on her. Come out and she starts no prob, again knock on wood Noticed a slight increase in mpg but she's a Jeep so I've come to grips w/ the gas mileage.
Question though; I was under the impression that aside from engine oil, the KJ used all syn fluids straight from the factory?

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2005 KJ Sport 3.7L, select-trac, trac-lok, K&N air, Mopar skids, 245/70R16 GY Wrangler Silent Armours, Draw-Tite Class III Max-Frame Hitch Receiver, PIAA Xtreme White Plus bulbs. Built: 08/04.
Exhaust, lift, rims painted black, Duralined, roof basket, and Renny light bar to come!
http://www.cardomain.com/ride/2305866
L.O.S.T. Member# 173501

Your t-case is still working even in 2wd. The t-case is connected to the trans and front and rear drive shafts connect to t-case.

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'06 CRD Sport, Silver build date 09/05
LoTek 2 pod pillar w/60 psi boost guage & egt
CRD Frankinlift, BFG-AT 31-1050/15 on crager soft 8's
Suncoast converter in a rebuilt trans with new pump and shift kit.
Yeah, It's got a diesel.

SOLD FOR GMC PICKUP

Correct.. Going to 4wd just transfers 50% of engine torque to the front wheels..

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LOST KJ'S
Where are you going???
Current Jeep: 2004 Jeep Liberty
-Atlantic Blue
-Air Ride Rear Suspension ; OME/Rustys Lift ; Powertrax Locker ; Moog Lower Ball-Joints ; 245/70/16 Yokohama Geolander A/T-S's on MOABS ; Flowmaster 50 SUV
Lost #007082
http://www.cardomain.com/id/jeepjeepster

Ok - you guys have me confused. I thought the ATF+4 used in the tranny and t-case was synthetic??? Also was under the impression that the 75-140 in the diff (tow pack) was also synthetic???? Front diff? not sure now? I'm referring to the Mopar - blends from the factory.

Somebody please help enlighten me.........

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05 BLACK KJ - 42RLE & NP242
Skids, Hooks, Bent Rock Rail, Lifted, A/T's, etc.
NY and PA and Florida ONF Special Custom Organic Trail Rash