JohnQ Posted July 31, 2006 Share Posted July 31, 2006 Which oil are we suppose to use? 5W-30 or 10W-30? I don't have an Owners Manual. Link to comment Share on other sites More sharing options...
Bounty Hunter Posted July 31, 2006 Share Posted July 31, 2006 Jeeps generally call for 10w30 or 10w40. Link to comment Share on other sites More sharing options...
Eagle Posted July 31, 2006 Share Posted July 31, 2006 In the last few years of the XJ lifespan Chrysler changed the oil to 5W30. That doesn't lubricate anything better, mind you, it just might gain a nano-MPG on the fleet average. Back in the time of the MJs the recommended weights were 10W30 and 10W40. Link to comment Share on other sites More sharing options...
JohnQ Posted August 4, 2006 Author Share Posted August 4, 2006 Thanks. I picked up some Mobil One 10W30 today. Now I just need to clean all the old sludge out of my engine. Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 4, 2006 Share Posted August 4, 2006 My 4banger MJ had 0W-30 in it when I bought it. I dunno, the whole '0W' part of that scares me. Link to comment Share on other sites More sharing options...
87manche Posted August 4, 2006 Share Posted August 4, 2006 my 4.0 likes 10w40. Link to comment Share on other sites More sharing options...
Eagle Posted August 5, 2006 Share Posted August 5, 2006 I ran the 88 XJ on 10W40 conventional for the first 175,000 miles of its life. When I finally switched to synth, the gauge was showing a bit lower than what I like (still well within spec, but lower than I like), so I now use Castrol Syntech 5W50. Although I suspect that the problem is with the gauge itself rather than the engine. I know it isn't the sender, because I've replaced that multiple times with neglible difference. Once the engine is warm, you can't run an oil that's "TOO" heavy. You need the lighter weight end of a multi-viscosity oil only to get quick oil circulation on cold starts. Link to comment Share on other sites More sharing options...
Bounty Hunter Posted August 5, 2006 Share Posted August 5, 2006 I just put in 20w50 and my oil pressure guage and I are much happier. Engine seems quieter and more smooth. This at 212K on the ticker. Link to comment Share on other sites More sharing options...
Oizarod115 Posted August 6, 2006 Share Posted August 6, 2006 my brother runs 20w50 in his 240k 4.0 with decent pressure. (and the poor thing turns 33's with stock gears) Link to comment Share on other sites More sharing options...
GirsMJ86 Posted August 6, 2006 Share Posted August 6, 2006 My 4banger MJ had 0W-30 in it when I bought it. I dunno, the whole '0W' part of that scares me. that is what i have in my 2.8 right now. we have 50gal drums of it here on the farm for the tractors. and to answer your question about what the w means. it has something to do with the oil being able to handle winter. it makes the oil warm up and run smoother sooner at lower temps. but it is fine all year round as long as you let your vehicle warm up first. its cheaper and does the same as 10w30. just make sure you let it warm up if its cold out. alex Link to comment Share on other sites More sharing options...
87manche Posted August 6, 2006 Share Posted August 6, 2006 I believe that DC was talking about the 0 weight viscosity properties when it's cold. That stuff pours like water. I wouldn't trust it in a 4.0. I'll stick to 10W40 and pay the .00005% mileage penalty for good oil pressure. Link to comment Share on other sites More sharing options...
cmcolfax Posted August 8, 2006 Share Posted August 8, 2006 my 4.0 likes 10w40. All I have ever ran in my 4.0L's. My XJ had 144K when I sold it. My ZJ has 109K. Prolly run the same thing in my 2.5L YJ when I get done. I am picky about my oil too... I run Valvoline MaxLife. Every third oil change I add a bottle of DuraLube http://www.duralube.com/itemInfo.cfm?itemID=57 Gotta get back in the habit of a bottle of Chevron Techron in the gas tank one tank before the oil change too. And I only run NAPA Gold, Purolator PureONE or WIX Premium filters. More info than you could ever want about oil filters is here: http://minimopar.knizefamily.net/oilfilterstudy.html And even MORE info than you could ever read about engine oils is here: http://www.bobistheoilguy.com/ -cmc- Link to comment Share on other sites More sharing options...
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