big66440 Posted January 15, 2016 Share Posted January 15, 2016 I'm going to be replacing my oil pan gasket and rear main seal soon and I was hoping to be able to use synthetic oil when finished but with all that mixed info on newer oil and the lack of ZDDP being bad for flat tappets I was wondering if you guys ( especially the guys running synthetic) would share what brand you use. I'm currently running Kendall 15W-40 diesel oil mixed with a quart of Brad Penn high Zinc 15W-40. Thanks Link to comment Share on other sites More sharing options...
Eagle Posted January 15, 2016 Share Posted January 15, 2016 Castrol Syntec 5W30 in winter, 10W40 in summer. Link to comment Share on other sites More sharing options...
gogmorgo Posted January 16, 2016 Share Posted January 16, 2016 Rotella T 5w40 right now. In summer 10W40. If the new(to my MJ) motor didn't burn as much as it does (waaaaay more than the last motor) I'd be running the T5. I ran 5w30 year-round in the old motor, and watched the oil pressure decrease until a severe bottom end knock developped. The two may not have been entirely related, but I don't care for it to happen again. Mind you, a $300 XJ is only six or so oil changes... Link to comment Share on other sites More sharing options...
64 Cheyenne Posted January 16, 2016 Share Posted January 16, 2016 Mind you, a $300 XJ is only six or so oil changes... Soooo true, my big problem is dealing with the empty shells Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 16, 2016 Share Posted January 16, 2016 In summer I use 15W50 mobile one synthetic and in winter I use 0W40 mobile one synthetic. With 240K on 1987 4.0 original engine and I have yet to see any burning oil since started using it in the early 1990's. I will do the same with my new MJ a 88 with new 4.6 crate engine. Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 16, 2016 Share Posted January 16, 2016 Rotella is good, but I prefer Chevron Delo 400 LE 15w40. Year round. It meets the API classification SM for older engines, and still has a minimum 1300 ppm zinc count, unlike Rotella ~1100 ppm, and is the only off-the-shelf motor oil I know of one of the few motor oils that still do. It's also approved by the manufacturer for both gas and diesel engines. The higher zinc content is beneficial for our flat tappet 4.0 engines, whether during cam break-in or maintaining longevity because it reduces the metal-to-metal friction no matter what the age/mileage. Chevron Delo 400 is a diesel spec motor oil and I've been using it for years in my Jeeps, but especially in the stroker with a mild cam. Link to comment Share on other sites More sharing options...
NorthWoods Posted January 16, 2016 Share Posted January 16, 2016 Same as eagle with 10w40 in the summer and 5w30 in the winter. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted January 16, 2016 Share Posted January 16, 2016 I got a deal on some NOS Mopar 15w40 diesel oil a couple years ago (11 gallons for $40). Ive been using it ever since. Seems to be doing good. Link to comment Share on other sites More sharing options...
91Pioneer Posted January 16, 2016 Share Posted January 16, 2016 Castrol regular 5W30, Mopar filter. No need for anything fancy considering how neglected my truck was when I got it. Link to comment Share on other sites More sharing options...
gogmorgo Posted January 16, 2016 Share Posted January 16, 2016 Haven't found the chevron up here yet, but if I could I'd run it for the summer. 15w40 isn't going to hack it up here in the winter... Couple days this week have been just above -30F in the morning. Link to comment Share on other sites More sharing options...
Lee21490 Posted January 16, 2016 Share Posted January 16, 2016 10w40 year round Pretty mild winter/summers in Washington. Maybe when i build a 4.7 i'll care enough to run full synthetic/etc. Link to comment Share on other sites More sharing options...
87Warrior Posted January 16, 2016 Share Posted January 16, 2016 I've run 10w30 Mobile 1 High Mileage and Mobile 1 filters in my Jeeps with great results. It is amazing how clean the oil becomes when drained after a couple years running full synthetic. My TJ has always run full synthetic oil since its rebuild 110k miles ago (except for the first 500 miles when I ran break in oil). To this day, it is still the smoothest and quietest 4.0 I have ever been around. A few years ago I lived in Vail, CO and had several -20F cold mornings and the Jeep didn't struggle to start once, even with 10w30 synthetic. Link to comment Share on other sites More sharing options...
Rockfrog Posted January 16, 2016 Share Posted January 16, 2016 Rotella 5w40 synthetic in both my 2000 XJ and my worn out (and I do mean worn out) 1988 MJ. Been thinking of slapping a poor man's backyard 4.7L together using a fairly decent 81 4.2L and an OK 93 4.0L and see what happens. The 4.0 still has decent bores so going to hack it and skip the machining. Will run the 5w40 as well. What's the worst that could happen? Hahaha! Link to comment Share on other sites More sharing options...
cruiser54 Posted January 16, 2016 Share Posted January 16, 2016 More importantly, which oil filters are you using? There's some real junk out there that can cause damage to our beloved 4.0s with the upside down mounting of the filter. Link to comment Share on other sites More sharing options...
jimoshel Posted January 16, 2016 Share Posted January 16, 2016 OIL?? Link to comment Share on other sites More sharing options...
neohic Posted January 16, 2016 Share Posted January 16, 2016 OIL?? Right?! Pretty sure that was put in from the factory. :idea: Link to comment Share on other sites More sharing options...
Rockfrog Posted January 16, 2016 Share Posted January 16, 2016 I swear that was the case with the PO of poor old Ratmanche ... Worst I've ever seen for crud inside any engine. I was amazed the rockers could move. The timing chain cavity was even worse. Sad, sad thing. As the rad crumbled in my hands ... He said "it does run a bit hot" ... Ya think? Link to comment Share on other sites More sharing options...
gogmorgo Posted January 17, 2016 Share Posted January 17, 2016 A few years ago I lived in Vail, CO and had several -20F cold mornings and the Jeep didn't struggle to start once, even with 10w30 synthetic. It's not the starting I'm concerned about, I know it'll do that. It's having something lubricating it for the first few seconds of running for every single start between October and April... 10w30 isn't horrendous with a block heater, but 15w40 is pushing it. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 17, 2016 Share Posted January 17, 2016 A few years ago I lived in Vail, CO and had several -20F cold mornings and the Jeep didn't struggle to start once, even with 10w30 synthetic. It's not the starting I'm concerned about, I know it'll do that. It's having something lubricating it for the first few seconds of running for every single start between October and April... 10w30 isn't horrendous with a block heater, but 15w40 is pushing it. All the more reason to have a quality oil filter with a good anti-drainback valve. Link to comment Share on other sites More sharing options...
75sv1 Posted January 18, 2016 Share Posted January 18, 2016 Shell Rotella 10W-30 year round and NAPA Gold. This is in my tow '98 XJs. I also ran it in my '88 Comanche. I might be switching to a synthetic in the Purple XJ. I replaced the oil boss oring and the oil consumption seems to be nil. The green one has always been nil, but trying to sell it. Probably use Rotella T6. Something with 1000-1200 ppm Zinc. Diesel oils usually do. I run the 10W30 Rotella in my MB 240D in the colder months. The MB guys say no, but the manual says Yeah. Then they say its not diesel rated. I say read the website. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 18, 2016 Share Posted January 18, 2016 Rotella and Napa Gold/Wix go together like peas and carrots.......... Link to comment Share on other sites More sharing options...
Rockfrog Posted January 18, 2016 Share Posted January 18, 2016 I've always used the Ford FL-1A, but that's just me. Same specs as stock short filter but twice the size. Link to comment Share on other sites More sharing options...
75sv1 Posted January 18, 2016 Share Posted January 18, 2016 Someone posted that WIX 51515 is an added capacity filter than the standard 4.0L filter. Also, NAPA dose have a Platinum line for Synthetic oils. Link to comment Share on other sites More sharing options...
wvzj Posted January 18, 2016 Share Posted January 18, 2016 Mobil Delvac or Chevron Delo whichever one has the best price at the time, both in the 15w-40 flavor. And of course a sexy Baldwin filter. Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 18, 2016 Share Posted January 18, 2016 Someone posted that WIX 51515 is an added capacity filter than the standard 4.0L filter. Also, NAPA dose have a Platinum line for Synthetic oils. Oversize Oil Filters (3/4"x16 thread) 5.178" HIGH, 3.660" DIAMETER AC-Delco PF2 Motorcraft FL-1A Purolator L30001 Napa 1515 Wix 51515 Mopar L-72 L-326, L-526, L-55, L-1007, L-138 Baldwin B118 Hastings LF115 Mobil 1 M1-301 Amsoil EaO15 Donaldson P550008 6.93" HIGH, 3.660" DIAMETER AC-Delco PF42 Motorcraft FL299 Purolator L40017 Napa 1773 Wix 51773 Mopar L-526 Link to comment Share on other sites More sharing options...
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