What type oil and filters are the best for the KJ?

Oh boy, an oil thread!

Assuming you are referring to the CRD KJ, I use a Purolator PureOne oil filter and Mobil1 Turbodiesel Truck 5W-40 full synthetic. For the fuel filter I use a Wix/ Napa Gold, and for the trans I use Napa filters with Valvoline ATF +4 full synthetic. (same fluid in transfer case and power steering, too) I also add some Powerservice silver or another fuel lubricant to every tank if I can't get a biodiesel blend.

I am at 88,000 miles now, bought it used in September 2008 with 24,000 miles on it. See my signature for my modifications.

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In this war of lines, so many have been crossed. Where will it all stop?

2006 Deep Beryl Green CRD Sport *SOLD 1/22/12*
Provent, V6 Airbox, Fumoto, Samcos, GDE ECO & TCM Tune, Euro JK TC, Magnaflow Catback
245/70/16 Destination A/T's
Boiler's Radiator Skid Plate
Jeepin' By Al 2.5 inch Adjust-A-Strut Lift, JBA Gen 4.5 UCA's (6/5/10)

...and since you're a registered user, the search function works wonders. You will find about 100 topics nearly identical to this one. They all have pretty much the same info.

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2005 Silver CRD Limited
245/75R16 GoodYear Duratracs
Fumoto drain | ProVent CCV Filter
Stanadyne FM100 filter | Cummins fuel pump
GDE Eco | SEGR | BoulderBars | FrankenLift | Frankenskids

I'll save you the hassle. Shell Rotella T6 ($19.50 for a gallon at Walmart) and Purolator Pure One filter ($9 at Advance Auto Parts) is all you'll ever need. Forget that ridiculously expensive Mobil1 that the owners manual specifies.

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2005 Stone White KJ Limited CRD 4x4
Off-Road Pkg
Trac-Lok
Emu 790s/948s
Skyjacker H7088s rear/Bilsteins front
15x7 Black Rock Lobos/31x10.50 Firestones
GDE HOT Tune + TCM Tune
Euro TC
CB radio
Thrush Turbo muffler
AEM DryFlow filter

Awww - but I like the MObil 1. Ive been using it for 92k and changing every 9-10 K. I've not had problems.

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2005 Black KJ Sport CRD,
GDE Full Torque ECO TUNE, GDE Transmission ECO Tune,
Samco British Racing Green Hoses
Build Date 1/05
200k miles.
Original Owner