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Unread 11-02-2010, 09:47 AM   #1
JimE2
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Best engine oil to use in a 4.0?

Getting ready to change my oil, and heard these straight 6's don't like synthetic oil, causes them to leak. Don't want to mess anything up, so I thought I would ask, for a Texas Jeep, what is a good oil to put into a TJ with 112K on it?

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Unread 11-02-2010, 09:49 AM   #2
Caribic-TJ
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yes, no need to buy expensive synthetic oil.
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Unread 11-02-2010, 09:51 AM   #3
JBTJ
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Quote:
Originally Posted by JimE2 View Post
Getting ready to change my oil, and heard these straight 6's don't like synthetic oil, causes them to leak. Don't want to mess anything up, so I thought I would ask, for a Texas Jeep, what is a good oil to put into a TJ with 112K on it?
That is like asking what is the best kind of air to breath. Any oil is good. That being said, I have three JEEPS with the straight six and use nothing but synthetic for the past 30 years. No leaks no problems. This is a can of worms where everyone will say something different.
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Unread 11-02-2010, 09:53 AM   #4
Night Wolf
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My oil of choice is Shell Rotella T/Chevron Delo/Mobil Delvac 15w-40.
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Unread 11-02-2010, 10:24 AM   #5
TheBoogieman
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Synthetic oil doesn't cause anything to leak.It finds spaces that regular oil can't get out of and does. Valvoline and Castrol GTX are good.
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Unread 11-02-2010, 10:55 AM   #6
Speed94
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what weight are you guys using?
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Unread 11-02-2010, 10:57 AM   #7
g4x4xgeoff
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I run 10w-30 castrol conventional in mine.
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Unread 11-02-2010, 11:09 AM   #8
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10w30 Quaker State High Mileage here. I know guys that have had this motor for years, and only bought what was on sale, never had a problem. Know guys that use Mobil 1 and have all kids of problems. Then again, I also know the complete opposite of what I just posted. So, to each their own. Each Jeep is completely different.
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Unread 11-02-2010, 11:30 AM   #9
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10w-30 GTX works good
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Unread 11-02-2010, 11:32 AM   #10
33shooter
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I have used Mobil 1 in every vehicle I've ever owned with great results. I would also suggest amsoil and royal purple as well, but those are expensive and not really worth it for engine oil IMO. I change my oil every 5-6k miles
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Unread 11-02-2010, 12:03 PM   #11
bairy
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The best oil to use is..... NEW OIL.

Just keep changing it.
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Unread 11-02-2010, 12:13 PM   #12
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Quote:
Originally Posted by bairy View Post
The best oil to use is..... NEW OIL.

Just keep changing it.
Yep.




If you drive a lot and put many miles on your TJ in a short amount of time then you could switch to synthetic just to gain some time between oil changes.
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Unread 11-02-2010, 12:30 PM   #13
JimE2
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Quote:
Originally Posted by TheBoogieman View Post
Synthetic oil doesn't cause anything to leak.It finds spaces that regular oil can't get out of and does. Valvoline and Castrol GTX are good.
Good point. Did not think of it that way. Makes sense to me!
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Unread 11-02-2010, 12:30 PM   #14
Woodenya
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Valvoline 10w30 is what I look for...
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Unread 11-02-2010, 12:32 PM   #15
JimE2
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Does it do any harm switching back to regular [new] oil, from, say unknown or possibly synthetic oil? I really have no idea what is in it right now, and want to switch to a known good oil of proper weight for Texas.
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