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  #1  
Old April 15th, 2019, 11:38
asymptonic asymptonic is offline
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Recommended Oil for a "New" Motor

I've just finished the appropriate mileage for breaking in a rebuilt Jasper motor. 98 XJ w/ 201k, 15k on the motor. I was considering going with a synthetic oil now but wanted to see what people think.


I will be avoiding Mobil 1, due to high iron readings in peoples UOA over at BITOG. But most of the advice I can find is for high mileage Jeeps, which technically I now don't have. I'll be changing the oil about every 5k so not really going for long OCIs. I'm looking for maximum longevity and MPG mostly.
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  #2  
Old April 15th, 2019, 11:54
RCP Phx RCP Phx is offline
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Re: Recommended Oil for a "New" Motor

Well since you didn't build the motor, you don't know what the specs are. With that about all you can go on is your ambient temps and your oil pressure.
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Old April 15th, 2019, 15:47
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Re: Recommended Oil for a "New" Motor

I just had this discussion with Russ Pottenger on what to run in my new stroker.

Not synthetic. No Pennzoil. No Quaker State.

If those are the guidelines for this $9000 stroker, probably good for your stock rebuild too.
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Old April 15th, 2019, 16:34
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Tim_MN Tim_MN is offline
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Re: Recommended Oil for a "New" Motor

Your low reving 4.0L was designed in the 1960's. Conventional oil will be both cost effective and meet the lubrication needs of the engine for hundreds of thousands of miles. Regular oil changes are more important than the brand name of the oil used or the oil type. My 1998 was a fleet vehicle for the first 2/3rds of its 284,000 miles and got regular oil changes with whatever lowest bidder oil was in the 55 gallon drum.
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Last edited by Tim_MN; April 15th, 2019 at 16:37.
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  #5  
Old April 15th, 2019, 20:07
SlowXj SlowXj is offline
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Recommended Oil for a "New" Motor

I've used Valvoline 10 30 conventional year around for 200k miles of my 400k mile pile of a motor. It's done me well.

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  #6  
Old April 15th, 2019, 20:28
asymptonic asymptonic is offline
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Re: Recommended Oil for a "New" Motor

Quote:
Originally Posted by RCP Phx View Post
Well since you didn't build the motor, you don't know what the specs are. With that about all you can go on is your ambient temps and your oil pressure.

Understood, RCP Phx. I'm the original owner of my Jeep and I know what to expect re pressures and temps. I swapped the motor out due to this being my daily driver and only vehicle and couldn't spend the 6-8 weeks without it to get it rebuilt locally. It hurt like hell to swap a motor out that I had maintained religiously for nearly 20 years but that was my only option. Wasn't cheap either.


In the process I replaced the radiator with an HD Mopar model and the temps have been rock solid in all conditions.


I'm not expecting a simple answer, just wan't to know what people think. With the current motor using PYB 10w30 I'm starting at 58ish PSI cold and warming to 21psi warm which feels fine. But in stop and go after warming I'm nearing 13-15psi via the gauge. I fought with the shop that installed the reman'd engine over oil pressure and then tested it myself to read 20psi warmed idle. They had put in an aftermarket oil sender and claimed it was MOPAR but it wasn't. The crap sender said 9-10psi warm idle but it was wrong. Replaced it with a legit sender and it agreed with a mechanical gauge.



So now I'm beyond break-in and ordinarily well within spec and want to know what oil I can try to keep it well within spec and extend this second motor to another 200k miles.


Sorry for the rant but this is my d__ned XJ and I want it to last.
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  #7  
Old April 15th, 2019, 20:46
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Re: Recommended Oil for a "New" Motor

I'm with slow. Valvoline 10w30 and run it.
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  #8  
Old April 15th, 2019, 21:14
Black1990jeep Black1990jeep is offline
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Re: Recommended Oil for a "New" Motor

10w30 Orielly brand regular oil in the 5 qt jug. low cost, seems to work.
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  #9  
Old April 16th, 2019, 03:19
RCP Phx RCP Phx is offline
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Re: Recommended Oil for a "New" Motor

Quote:
Originally Posted by Black1990jeep View Post
10w30 Orielly brand regular oil in the 5 qt jug. low cost, seems to work.
I wouldn't stoop that low!

OP, it sounds like 10-30 is working for you. I was talking about "ambient temps" because I live in Az where it gets over 120* out. Make sure you get something with adequate ZPPD (you can also purchase it as a additive). I'm anal about my engines so I've been running WIX filters and Amsoil for 50yrs now.
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  #10  
Old April 16th, 2019, 05:07
CJR CJR is offline
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Re: Recommended Oil for a "New" Motor

" Rotella: The world's first ever combined hair oil, foot ointment, and salad dressing"

Do a search on the above sentence in quotation marks and it will enlighten you. I've been using Rotella oil for quite awhile and I'm very pleased with it.

Best regards,

CJR
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  #11  
Old April 16th, 2019, 07:44
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8Mud 8Mud is offline
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Re: Recommended Oil for a "New" Motor

My motorcycle specified non-synthetic oil, I used Valvoline. Used Valvoline in my Cherokees for decades. I buy from a wholesaler in five gallon cans.

I pretty much gave up on synthetics when the EPA forced them to reformulate, which degraded many of the pluses.
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  #12  
Old April 16th, 2019, 07:55
asymptonic asymptonic is offline
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Re: Recommended Oil for a "New" Motor

Quote:
Originally Posted by RCP Phx View Post
I wouldn't stoop that low!

OP, it sounds like 10-30 is working for you. I was talking about "ambient temps" because I live in Az where it gets over 120* out. Make sure you get something with adequate ZPPD (you can also purchase it as a additive). I'm anal about my engines so I've been running WIX filters and Amsoil for 50yrs now.

Yep, I run the Wix 51515. I'm a little concerned about my hot idle. If I drive highway in the heat then hit stop and go city, it'll drop to 15 or so, which for a new motor feels low. Seems to me the PYB really thins out hot. Texas here so not 120 but it does get hot.
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Last edited by asymptonic; April 16th, 2019 at 08:21.
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  #13  
Old April 16th, 2019, 19:20
trippled trippled is offline
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Re: Recommended Oil for a "New" Motor

Quote:
Originally Posted by Black1990jeep View Post
10w30 Orielly brand regular oil in the 5 qt jug. low cost, seems to work.
Last time I asked them at O'Reilly they said it's made by Valvoline. I've run it too. More than anything proper oil change interval is key. Anymore I run whatever looks good at the time. As long as it's Valvoline mobile or rotella.

I'm starting to think the whole zddp thing is a crock. If it was the only thing capable of keeping cams alive damn near everyone here would have a flat cam. I have no evidence but I believe there are other additives that keep cams alive in new oil. Oil has to do a lot more now than it did 50 years ago.
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  #14  
Old April 17th, 2019, 15:18
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4x4JeePmaNthINg 4x4JeePmaNthINg is offline
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Re: Recommended Oil for a "New" Motor

Valvoline 10w-30, ran it for 10 years. Switched to high mileage blend two years ago, not sure it's any better. Thinking conventional 10w, or 5w for winter will do just fine.

Maybe it's just me but I always thought I could tell a difference after oil changes with conventional, anyone else ever think so?
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  #15  
Old April 17th, 2019, 15:21
SlowXj SlowXj is offline
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Recommended Oil for a "New" Motor

I had an old Ford work van and I could tell when it was oil change time by fuel mileage... In 4k miles it would drop 2mpg! I've never seen another vehicle do that... Lol

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