What is the best oil for a highmileage jeep? what kind does everyone use?

As your engine wears, it is wise to put some heavier oil in it. I use Valvoline 20W50 Racing. The racing oil is designed to burn a little, as a racing engine does and not leave any deposits on your plugs. They will stay clean even if you do burn it.

how many miles do you have on it? i have about 143k on a 96 with a rear main leak (i think, havent verified this yet) and my check engine light is on (i think my oils getting a little low but not sure either haha) but i need to make sure everythings ok in the next two weeks before i go back to school. i dont need an oil change for another 1000 miles but i might just do it a day or two before i leave, i wanna move up to a heavier weight and maybe get some lucas stabilizer. i was just wondering what to get to work on that rear main leak for a while.

theres a pretty recent forum on naxja thats about 3 pages long on this same topic i think haha.

Nothing will solve the rear main except fixing it. y engine is a Chevy with about 200,000 on it. It does have a little blow by which is recycled back into the engine. My plugs stay clean and my oil pressure very good.

Ive got 176,671 miles on my jeep

I have been using Valvoline High Mileage in Factory weight with excellent results. I have 177,xxx on the engine. My oil filter adapter leaks but will be fixing that here soon. I have heard Shell Rotela is a great option. I will be switching to that for the next oil change.

Rotella 15-40, and it still contains zinc, which most conventional oils have eliminated from their oils.

I have 260,000 on my jeep being an 87 it doen't leak (after fixing all of them) or seem to burn any oil, so I have been running castrol 10w30.Its all about regular maintenence.

so zinc in oil is bad?

Zinc is not bad.

I use Mobil 1 High Mileage 10w30.

That's the one i use too except it's 20W 60 sinthetically based, a little better on high temp (220k). Stay away from the newer 5W 50, 10W 50, and 15W 50, they lose their viscosity very fastly and act like a common 5W 30 10W 40.

I'm currently using AMSOIL 20-50 high zinc formula, expensive? yes. worth it? I think so.
Its high-mileage stuff, and at $2 more per quart than castrol, its not that much of stretch for me.

Mobile 1 clean high mileage oil 10W-30, with heavy duty oil filters by Fram. I change the oil every 2500-3000 depending on heat and usage.

thank you very much all of this has been very help full

That's pretty much what I do on my '90 Laredo, too, and I'm over 230K miles without issue.