should I use synthetic Blend oil or just oil in my 2003 wrangler X 4.0 with 80,000 miles
What have you been using? If it has been just convential oil you can if you like. But if it isn't using any more than a quart of oil between changes then why bother with the increased expense. Just keep the maintance up and you shouldn't have any problems.
Then stick with what the previous owner was using, once you start with any kind of synthetic you should stick with it, there have been some reports of oil leaks showing up after switching back to convential oil from synthetic.
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