Should I go full synthetic or part or regular oil with a 4.0L 103k miles? -
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Go Back > General Technical Discussions > Engines & Drivetrain > Should I go full synthetic or part or regular oil with a 4.0L 103k miles?

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Unread 12-19-2003, 03:04 PM   #1
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Should I go full synthetic or part or regular oil with a 4.0L 103k miles?

Like the title says, I just bought an XJ with 103k miles (4.0L 93 Cherokee sport 5spd). I have always used synthetic on my Toyota's and Honda's with high miles, but I'm new to the Jeep's 4.0L engine. Will there be a prob with running Castrol Syntec blend with this many miles on the motor? What are everyones opinion on oil types for this Jeep? My concern is running a cleaner oil (synthetic) which could clean out the oil passages and in result cause the jeep to have some small oil leaks around gaskets and rubber and such. What do you all think?

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Unread 12-19-2003, 03:12 PM   #2
tubework is cool...
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personally...I'd go with a good quality "normal" oil, and change it regularly...

you might try a blend if you wish, but unless the first 103K were with synthetics I probably wouldn't switch...for the same reason you mentioned (just worded a little different)...the synthetic won't "cause" any leaks, but it mind "find" some that were already there but clogged up...

I've never been a fan of synthetic motor oils, but I do like synthetic greases and gear lubes...

just my $.02...

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Unread 12-19-2003, 03:27 PM   #3
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Use whatever was put in it by the previous owner. Whatever it was, it worked for 103k and kept the engine in good shape, right, or you wouldn't have bought it.
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Unread 12-20-2003, 02:10 PM   #4
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I agree with BigWaylon. The syntheic might dissolve some sludge around the seals and then you could start leaking oil. Now, thats not necessarily a bad thing cause then you would know what seals, etc needs replacing, but its up to you. I use Amsoil synthetic in all my vehicles, but I've had them since they were new.
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