Jeep Wrangler TJ 4.0 Oil

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New to me 2004 Wrangler TJ with 4.0. 105,000 miles and well taken care of; would like to keep it that way. Thinking either regular Pennzoil 10w30 or Rotella T5 10w30. Does the Rotella still have the ZDDP that I see recommended? Would the ZDDP harm catalytic converter? I'm a big fan of Rotella T 15w40 and run it in all of my motorcycles. Thoughts?
 
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The 4.0 isn't terribly demanding on oil. Once broken-in, the flat tappet cam will be perfectly fine on today's SN oils with ~800 PPM of ZDDP. That said, the 4.0 is prone to low-ish oil pressure as it racks up miles, and tends to do extremely well on 40-weight oil instead of the manual-recommended xw30. Rotella T6 5w40 is an *extremely* popular choice in the 4.0, and being a 40-weight it is allowed ~1000 PPM of ZDDP for those who want the extra peace of mind. Unless that thing is burning a quart of oil every 500 miles, modern Xw40 levels of ZDDP will not hurt the catalyst. It was *designed* when all the available oils had more ZDDP than most today have.
 
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I put some 5W30 PHM in my 4.0 XJ and it seems quieter. Did 5W30 for the winter since it'll be below 0 often. Switch back to 10w30 after. It's only been a week or two, but it seems to be cleaning it up. Not sure if it's slowing the leaks yet.
 
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Rotella T5 in 10w30 is a great oil for that engine. I ran it for years in a 4.0 GC and not issues when sold at 155,000 miles. Ops I did need a new rear main seal every 75,000 miles. Ed
 
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The 4.0 in England calls for either a 5w40 or 15w40 depending on temperature.. you'll be fine with a 15w40. As said, the ZDDP isn't a cat-o-strophic issue either.. Nor do the engines "need" it. All of your suggestions sound good. My Jeep has been on the PYB diet for the last 40k and a 5w40 synthetic diesel oil diet the 35k before that.. I am either going to try the Castrol Edge HM 10w40 next (similiar to what I am running now) or Rotella T6.
 
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Originally Posted By: jayg
Originally Posted By: Chris142
mine seems sluggish with 15w40
It's a TJ. That's your sluggish problem.
not really. no lift,only 31's,3.73 and 5 speed.it gets up and goes pretty good.
 

Nick1994

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Originally Posted By: jayg
Originally Posted By: Chris142
mine seems sluggish with 15w40
It's a TJ. That's your sluggish problem.
You must not have driven very many Jeep 4.0L's. As Chris said, they get up and go pretty good.
 
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Short of a very hot climate I think 15w40 is overkill. A syn blend 5w or 10w40 is what I'd pick, though a good 10w30 won't hurt if oil pressure is good enough. I had Schaeffer's 15/40 in my '85 GMC 454 and switching to their 10/30 made it so much more limber it was surprising.
 
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Originally Posted By: Nick1994
Originally Posted By: jayg
Originally Posted By: Chris142
mine seems sluggish with 15w40
It's a TJ. That's your sluggish problem.
You must not have driven very many Jeep 4.0L's. As Chris said, they get up and go pretty good.
Driven plenty. It was a joke. And that's relative.
 
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A TJ feels like a Ford Raptor compared to my WJ. ...Glad I have a straight 6. A V8 would get me into trouble.
 
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Have owned a 2005 Wrangler since 2007. For the first 8 years I used Rotella 15-40. About 2 years ago I switched to QS Defy 10-30.....have been happy with the switch.
 
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