What kind of high was Merle on??

What kind of oil should i get for a high mileage Jeep Grand Cherokee ?

• I'm going to change the oil in my mom's Jeep this will be my first time ever changing oil in a car, but it doesnt sound hard. Just warm the car up, turn it off and unplug the oil bolt on the pan and have it drain into the container to catch the oil. Then let it drip until its all gone, take out the old oil filter, and replace it with a new one after oiling the seal's around the filter. Then fill it back up, check the oil level run the engine for a little and check the oil level again. Ok so i get that, but what im wondering is what kind of Oil should i buy for a Jeep Grand Cherokee Inline 6 4.0 with 160k Miles ? Ive asked my mom what kind of oil she put in the car when it was last changed but she doesnt know only that it was high mileage oil. I suspect it was some kind of generic high mileage oil because the oil change only costed her $20. She also doesnt know how many miles its been since she changed it i suspect around 3-5k miles. I checked the oil on the dipstick and its pretty much dark brown/black color so i think it needs changed. The manual says to get 10w30 multi-viscosity oil, but there are so many brands..

• Answer:

  use valvoline 10w30 high mileage oil. do not use Pennzoil or quakerstate. they will leave a heavy sludge in the oil pan and valve cover. i have first hand knowledge of this. i have overhauled about 50 engines and the ones that ran pennzoil or quakerstate had a thick sludge buildup. i personally use shell rotella t 15w40 in the summer and valvoline high mileage 10w40 in the winter. no sludge buildup at all.