What oil Should i use ?!?!?!
I don't know about you but I don't like sluge in my moter. I'm not afrade of replacing a gaskit for a clean moter. And his gaskit was bad before the syn oil gtx dosnt have enuf zink and phos. And I use to run q as well until I noticed a valve tick it was the q oil or the k and m oil filter.
Senior Member
Joined: Mar 2010
Posts: 550
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From: upstate NY
Year: 1998
Model: Cherokee
Engine: ???
I use Castrol GTX High Milage and its great in my 200000+ mile daily driver. I would only use full synthetic in a newer or just rebuilt engine(under 100000 miles), especially durring break in. I also use a 25% mixture of Lucas Oil Stabilizer. If youre gonna switch oil brands and and or go from regular to synthetic, I would highly recomend doing an engine flush.
Just my 2 cents though...
Just my 2 cents though...
Senior Member
Joined: Mar 2010
Posts: 550
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From: upstate NY
Year: 1998
Model: Cherokee
Engine: ???
I don't know about you but I don't like sluge in my moter. I'm not afrade of replacing a gaskit for a clean moter. And his gaskit was bad before the syn oil gtx dosnt have enuf zink and phos. And I use to run q as well until I noticed a valve tick it was the q oil or the k and m oil filter.
CF Veteran


Joined: Jan 2010
Posts: 1,456
Likes: 74
From: North Riding of Yorkshire, UK
Year: 1997
Model: Cherokee
Engine: 4.0
Just use whatever grade it says in the handbook. There's nothing to be gained from second guessing the people who designed the engine and were liable for warranty claims.
Synthetic oil is great, and won't cause leaks. But it is also totally unecessary on these old boat anchors unless you're going for a massive drain interval. My recommendation would be a mid quality semi-synthetic. That's all it needs.
Lucas (and all other oil additives) are totally redundant if you've got decent oil and change it when it is due.
Synthetic oil is great, and won't cause leaks. But it is also totally unecessary on these old boat anchors unless you're going for a massive drain interval. My recommendation would be a mid quality semi-synthetic. That's all it needs.
Lucas (and all other oil additives) are totally redundant if you've got decent oil and change it when it is due.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Just use whatever grade it says in the handbook. There's nothing to be gained from second guessing the people who designed the engine and were liable for warranty claims.
Synthetic oil is great, and won't cause leaks. But it is also totally unecessary on these old boat anchors unless you're going for a massive drain interval. My recommendation would be a mid quality semi-synthetic. That's all it needs.
Lucas (and all other oil additives) are totally redundant if you've got decent oil and change it when it is due.
Synthetic oil is great, and won't cause leaks. But it is also totally unecessary on these old boat anchors unless you're going for a massive drain interval. My recommendation would be a mid quality semi-synthetic. That's all it needs.
Lucas (and all other oil additives) are totally redundant if you've got decent oil and change it when it is due.
CF Veteran
Joined: Apr 2009
Posts: 1,109
Likes: 3
From: Austin, Texas
Year: 1991
Engine: 4.0 I-6 H.O.
synthetic is not thinner, the 10W30 is the viscosity which is basically a measure to how thick an oil is
the reason people think synthetics cause leaks is because all synthetics have detergents and additives in them, most of which are used to clean bearing surfaces of gunk and what not, Usually its the case that a gasket will fail in a certain area, but because conventional oil has passed through the hole in the gasket it will be eventually plugged up by gunk
WELL the plugged holes will get "cleaned" by the synthetic oil which will cause the previously plugged leaks to reappear
the reason people think synthetics cause leaks is because all synthetics have detergents and additives in them, most of which are used to clean bearing surfaces of gunk and what not, Usually its the case that a gasket will fail in a certain area, but because conventional oil has passed through the hole in the gasket it will be eventually plugged up by gunk
WELL the plugged holes will get "cleaned" by the synthetic oil which will cause the previously plugged leaks to reappear
CF Veteran
Joined: Apr 2009
Posts: 1,109
Likes: 3
From: Austin, Texas
Year: 1991
Engine: 4.0 I-6 H.O.
I don't know about you but I don't like sluge in my moter. I'm not afrade of replacing a gaskit for a clean moter. And his gaskit was bad before the syn oil gtx dosnt have enuf zink and phos. And I use to run q as well until I noticed a valve tick it was the q oil or the k and m oil filter.
http://glynmora.com/WidderWoman/wp-c...n-Keyboard.jpg
How did you know I use my black barry to post? Well never passed a spelling test eather. But last I checked you don't need to be an english teacher to turn a wrench. I'm just an old (25) farm boy who dropped out of the birth canail with a wrench in my hand. By the way about my parents I don't ask when I really don't want to know!
CF Veteran
Joined: Jan 2009
Posts: 2,199
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From: Britt, MN
Year: 1998
Model: Cherokee
Engine: 4.0
I like your style.
I have argued this to the point of just saying heck with this thread lol.
2000 XJ- High Zinc Formula 10w-40 or Diesel Spec Amsoil. 138k
1988 MJ- Rotella 15w-40, with Lucas if i remember. but it just leaks oil anyway.
I also refuse to use a FRAM filter because of the common bad drainback valve. I will only use WIX or Amsoil filters. I have found that an amsoil filter is really no more better then a WIX.
A flat tappet engine like the 4.0 or 2.5 LIKE zinc. So any oil with a high zinc content would be your best bet. Arguing about oil is like arguing about what beer tastes better...
I have argued this to the point of just saying heck with this thread lol.
2000 XJ- High Zinc Formula 10w-40 or Diesel Spec Amsoil. 138k
1988 MJ- Rotella 15w-40, with Lucas if i remember. but it just leaks oil anyway.
I also refuse to use a FRAM filter because of the common bad drainback valve. I will only use WIX or Amsoil filters. I have found that an amsoil filter is really no more better then a WIX.
A flat tappet engine like the 4.0 or 2.5 LIKE zinc. So any oil with a high zinc content would be your best bet. Arguing about oil is like arguing about what beer tastes better...
Senior Member
Joined: Jan 2010
Posts: 999
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From: Brentwood, TN
Year: 2001
Model: Cherokee
Engine: 4.0
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
synthetic is not thinner, the 10W30 is the viscosity which is basically a measure to how thick an oil is
the reason people think synthetics cause leaks is because all synthetics have detergents and additives in them, most of which are used to clean bearing surfaces of gunk and what not, Usually its the case that a gasket will fail in a certain area, but because conventional oil has passed through the hole in the gasket it will be eventually plugged up by gunk
WELL the plugged holes will get "cleaned" by the synthetic oil which will cause the previously plugged leaks to reappear
the reason people think synthetics cause leaks is because all synthetics have detergents and additives in them, most of which are used to clean bearing surfaces of gunk and what not, Usually its the case that a gasket will fail in a certain area, but because conventional oil has passed through the hole in the gasket it will be eventually plugged up by gunk
WELL the plugged holes will get "cleaned" by the synthetic oil which will cause the previously plugged leaks to reappear
Seasoned Member
Joined: Jan 2010
Posts: 251
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From: JERSEY ALL DAY
Year: 1989
Model: Cherokee
Engine: 4.0L
I had a brand new motor dropped in and had them fill with 10w30 Mobil one. Haven't even had its first oil change yet. Seems to be doing well so far. Before that I ran the same on 163000 mile engine and it was fine til it died. I've heard that once you run synth to not swap back but that's just what I heard. Its up to you really and like everyone else said try to find out what the po used.
As for me i run wallmart synthetic...that supertech crap. Good insurance running a synthetic it will keep everything clean. If i spring an oil leak, ill just fix it, just like im sure anyone else would do. But im OCD with my cars..however, i cant see why you would run mobil 1 synthetic...its overkill IMO, whats the need its not a race motor, its not boosted, its certainly not running 13s, or making any kind of power. I love my jeep. I save the mobil 1 for my stang.
Senior Member
Joined: Jan 2010
Posts: 999
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From: Brentwood, TN
Year: 2001
Model: Cherokee
Engine: 4.0
So whats the deal? Does synthetic oil ruin high mileage engines like others here say, or is it fine? I am using the high mileage synthetic blend that seems to be working out pretty well. The valvoline high mileage synthetic blend I use has zinc.


