I have a 1997 straight 6 4x4 Grand Cherokee with 153,147 miles on it and I was wondering whats the best kind of oil to use in it? Also I just discovered that my front passenger floor is wet and think its the heater core! How hard is it to fix and about how much will it cost? Last thing how can i(cheaply)get more power out of my old jeep? It just doesnt seem to have the climbing power it used and I live in western Pa so when I drive it it constantly is climbing hills! Its one of the best looking 1997s left on the road and I really dont want to see it die or get weak on me! CAN ANYONE HELP ME???????

 

That's a nice looking ZJ alright. And Welcome to CF.
Does that wet floor smell like coolant, or is it condensation from a plugged A/C drain? If it's the later, check out this link.

 

with the power thing AVOID TB SPACERS! they are useless, go with a a full exhaust ($$$), or a cat back system ($$), or heck most mufflers will give you something of an improvement ($)
you can also do an air intake, some will argue that they dont give you any increase but imo they do, also with that if you live in a really dusty area dont get a k&n (there was a study done that shows that they let a lot of dust and sand in)

oil, i go with a 10w 30, the real stuff not the synthetic.

 

Thanks. No i dont have any problems with dust. I live in western Pa so its the hills. thats where i really notice the lose in power wen i start up a hill going 40 and by time im half way up im at 30 and i feel like im forcing it. i dont know if thats just because its a straight 6 and is geared really low cause it doesnt do good on highways either. but it has plenty of slow climbing power. I was thinking of switching to a synthetic or super thick oil because of the high miles?

 

Synthetic's okay but I'd stay away from too thick of an oil. 10W30, or 10W40 is what I use and my '97 has over 187,000 miles on it and doesn't use half a quart between changes.
Mine has 3.73 gears (and the V8) so that helps a lot. It would help a lot if you kept it out of OD when driving in the hills. It raises the RPMs, and keeps the engine more in its power-band. OD is 4TH gear by the way. I always turn off OD when driving in hilly terrain or towing.

 

i have a k&n air filter and i love it!!! i also have a flowmaster muffler with no cat. and i notices a good difference in power just having those two combined. if your cat is getting clogged (which will happen over time especially with high miles and having to climb hills all the time) that will rob the power from your motor big time from your exhaust not being able to flow. everytime i take my air filter off to clean it my intake is as clean as a whistle so i disagree with the dirt and sand thing. i live in the desert too!

 

also i like the royal purple full synthetic oil and i feel a power difference running that as opposed to regular motor oil.