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Unread 03-24-2009, 04:26 PM   #1
redman1567
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2008 JK Wrangler 
 
Join Date: Jun 2007
Location: Milwaukee
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Motor Oil for 85 258

I know that everyone says different things and recommends different things for motor oil, but i was wondering if anyone can tell me whether i should use conventional or syntetic motor oil in my 85 cj7 and why. Thanks.

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Unread 03-24-2009, 04:30 PM   #2
SuB8HaVeN
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I'd run nothing but conventional in a seasoned pushrod I6. Better yet run Rotella diesel oil or Penzoil Long-Life (diesel oil).
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Unread 03-24-2009, 04:35 PM   #3
BioTex
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X2 on the Rotella, however I'm tempted to throw in a quart of synthetic just to get the extra friction protection, but am unsure if it will do any good. I'd love to know the facts on that.
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Unread 03-24-2009, 04:37 PM   #4
Mike Romain
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I am also running diesel engine oil in mine. The engine calls for 10W30 for normal use, but the new gas engine oils are lacking additives the older ones need and the diesel oils still have them.

A synthetic will also clean out your engine so if you don't have all brand new seals it will turn into a pincushion.
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Unread 03-25-2009, 01:36 AM   #5
Lawless_Jeep
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I run conventional Valvoline 10w30 during the winter months, and Rotella 15w40 in the summer months. Rotella because of the zinc content keeps wear down.
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Unread 03-25-2009, 12:01 PM   #6
jeepmaniac
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Rotella is also available in 5W-40 synthetic (got it @ Walmart) - for those folks that reside where there are only 2 season - winter and road construction.
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Unread 03-25-2009, 12:26 PM   #7
mcmud
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1983 CJ8 
 
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Read about the Rotella 15/40 very soon after joining in on forum discussions. Quickly learned to trust the sources of info and tried it. Only engine oil I buy today. Even adding in for the recommended extra filter changes during the engines clean out period that cost and effort sure beats valve train rattles and worries.
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Unread 03-25-2009, 12:40 PM   #8
Fjguercio
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1978 CJ7 
 
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Location: Burnsville, MN
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I run conventional oil, shell Rotella T Diesel Oil. Menards has it a at a great price. Has the ZDPH. Others, some of the diesel oils, off road, racing oils still have the ZDPH. I am also one of the guys that made quite a fuss about this.

JeepHammer say kinda a waste to put synthetic in a carbed engine. Our low HP, low rev, carbed engines that are usually rich will contaiminate the oil before the extened change cycle. That makes good sense.

One exception for the synthetic..... If you use the CJ in the Very Cold climates, like MN, the synthetics do not get as thick and may offer more protection.

For the poster above... I would not use the 40w for winter use. Too thick and may pump up the lifters too much and cause some issue and valve trane noise. Saw you were from MN. FYI.

Last... do not use the Frame Oil Filters on the 258, the allow the oil to drain out and have more of a dry start issue. They were also rated poorly for filter quality. Some good articles on both filters and oils if you do search. I found a great buy on Mobil 1 filters a yr ago $4 each and stocked up. Wix and few others were rated better.

Regards,
Fred
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Unread 03-25-2009, 01:14 PM   #9
Drsafety
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You may want to read the following thread:

http://www.jeepforum.com/forum/f8/shell-rotella-t-my-jeep-578698/

I use Shell Rotella in my Jeep.

Hope this helps...
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Unread 03-25-2009, 03:44 PM   #10
jeepmaniac
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Fred,
Just a comment on your reply - I agree that conventional 40w oil is too heavy to use in a cold climate like ours, but as you stated, synthetics are great in colder temps because of the better flow characteristics. I used Castrol Syntec 5W-50 in my 360 for many years (all year long) with no problems whatsoever. Always started - even at -25 deg. That engine is still in use after 135,000 miles since rebuilding. The Rotella 5W-40 is a synthetic.
Not trying to start a big issue here - just my personal experience.
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Unread 03-25-2009, 05:20 PM   #11
Fjguercio
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Quote:
Originally Posted by jeepmaniac View Post
Fred,
Just a comment on your reply - I agree that conventional 40w oil is too heavy to use in a cold climate like ours, but as you stated, synthetics are great in colder temps because of the better flow characteristics. I used Castrol Syntec 5W-50 in my 360 for many years (all year long) with no problems whatsoever. Always started - even at -25 deg. That engine is still in use after 135,000 miles since rebuilding. The Rotella 5W-40 is a synthetic.
Not trying to start a big issue here - just my personal experience.
Jeepman,

I understand what you are saying. The FSM's and other auto documentation specifly motor oil weight to the temperatures. We live in MN and can get to 5 to -25F pretty often like we saw this winter. The FSM recommends above 0 deg F 10w30 or 10w40 (single weight 20w) and below 0 F 5w20 or 5w30 (single weight 10w).

No argument, use what you want. When you tell others on the JeepForum its ok to use a 40W there should be some caution. Now you say use a 50w. I do take acception with the 50W.

The Vintage Jeeps use a flat lifter that has a reed valve. Too Thick an oil will have more reisitance flowing thru the reed valve and may over pump up the lifter. Not a good thing.

Many of the JeepFourm Folks can get away with the 10w40 but here in MN just too cold. YES it is IMO. But the FSM agrees with me.

I store my CJ in the winter and salt. I am using 10w30 on the newly rebuilt engine. After 5k to 15k miles i may change to the 10w40 during the very hot summer months if I do another oil change. All the break in on mine will be done with 10w30W Shell Rotella.

Take care,
Fred
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Unread 03-26-2009, 10:43 AM   #12
jeepmaniac
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Posts: 142
Fred,
Well - here we go...I did not recommend using any specific weight of oil - I just presented what has worked for me. I based some of my comments on a lengthy and thorough scientific article (38+ pages - wish I could find it for you, but can't) about how different weights of oil work in an engine. According to this article - there is very little difference in how 20W, 30W, 40W or even 50W work in an engine at operating temperature. The issue in cold climates is how well the oil flows when the ambient temperature or engine is cold - how well the oil is able to reduce friction and wear before the engine reaches full operating temperature. I do agree that a 5W oil is appropriate for our cold climate, but also think a higher weight synthetic oil ( not conventional oil ) is OK to use because of the improved flow characteristics of synthetics.
You refer to specs in the FSM that was written 35+ years ago - well before synthetic oils were available to the average consumer.
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