post #871 of Old 10-07-2010, 02:44 PM
CB3
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Here is a big P.S. about all brands of full synthetic 5/40 in a 4L engine.

Since most damage from lack of ZDDP occurs at start-up (before oil is flowing to top of engine), this is a huge reason I like 5/40 full synthetics. The 5/40 synthetics excel at cold startup lubrication and also at high heat lubrication too. They have a wider operating temperature range.

5/40 full synthetics have more ZDDP, AND they flow to top of engine faster and give full oil pressure faster at cold startup due to the 5/X weight flowing faster at cold start. AND X/40 full synthetics maintain proper oil pressure at full operating temperature.

The X/40 rating is needed for a full synthetic to have normal/proper oil pressure at full op temp because full syn is slipperier than conventional oil. Slipperier oil reduces oil pressure. So a larger high number rating is needed to compensate.
For example: At full operating temp, a full syn 10/30 gives low oil pressure compared to a conventional 10/30. A full syn X/40 gives same (proper) oil pressure compared to a conventional 10/30.
So there are a whole bunch of reasons why a full synthetic 5/40 makes good sense in any 4L engine that's NOT an oil burner, and why a synthetic blend 10/40 makes good sense in an oil burner.

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post #872 of Old 10-07-2010, 09:22 PM
TheFog
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Since ZDDP is becoming the big discussion point I found a write up on the Corvette action center webpage about just what exaciatly ZDDP is.


Why ZDDP Gets so Much Attention

The most common EP additive in automotive engine oils is zinc dialkyldithio-phosphate (ZDDP), a family of coordination compounds of zinc and dithiophosphoric acid which, in longer chain, molecular derivatives, easily dissolve in engine oils. Known more commonly as "zinc dithiophosphate" (ZDP), "zinc phosphate" or, quite incorrectly, just "zinc", this compound was initially added to oil in the 1940s as an anti-corrosive/antioxidant. Later it was discovered to be an excellent extreme pressure lubricant.

When subjected to heat present at the lobe/lifter interface, ZDDP decomposes into alcohol, zinc, sulfur and phosphorous. The alcohol
evaporates and the zinc mostly washes away, leaving sulfur and phosphorous to combine with iron molecules on the surface of the cam lobe to make iron sulfide and iron phosphate, the two compounds which perform EP lubrication.

"The 'dithio' in 'zinc dithiophosphate' means for every phosphorous there are two sulfur molecules," Red Line Synthetic Oil Corporation's Vice President and top petro-chemical engineer, Roy Howell, told the Corvette Action Center.

Sulfur is probably more important than zinc and phosphorous. The cam and lifter wear surfaces are rich in iron and sulfur with a lesser amount of phosphorous. The ZDP decomposes into a soft, thin film of iron sulfide and iron phosphate which prevents iron adhesion, or welding. The zinc doesn't do much. If you look at photomicrographs of cams and lifters, there's hardly any zinc coating, but there's a lot of iron sulfide coating and some iron phosphate coating.

With this process, you trade adhesive wear for chemical wear. If you didn't have these soft films, which prevent iron from touching iron if you didn't have something in the middle, then you'd get adhesive wear-welding and that iron-to-iron weld would pull 'chunks' out of the lobe and follower.

What makes zinc dialkyldithiophosphate unique is its precise thermal decomposition temperature which can be manipulated by changing the composition of the organic alkyl group attached to the phosphorous.

If it decomposes at too low a temperature, chemical wear would occur where it is not needed but, if it occurred at a higher temperature, then some adhesion or welding, would already be taking place.

There are a lot of different sulfur compounds Howell continued, but this one has 'precision-controlled' decomposition. In many of the
others, the sulfur and the phosphorous are much more loosely bonded. There's a bigger 'range'. It might partially decompose at a lower temperature and finish at a higher temperature or, maybe, decompose only at a higher temperature, however, with ZDP-boom!-, like at 400°F, it starts to thermally decompose then react with the surface of the lobe and lifter to form those almost monomolecular soft films. As the lobe rubs against the follower, that film will get rubbed off and in the next revolution, the same thing happens again."

ZDP is slowly depleted by decomposition and evaporation, so eventually EP lubrication becomes inadequate. This is one reason oils need to be changed periodically.

While some petrochemical engineers consider sulfur of primary importance and some consumers misunderstand zinc content as benchmarking EP additives in oil; in reality, it is the phosphorous component about which the oil industry is most concerned.

http://www.corvetteactioncenter.com/..._camwear2.html



FOG
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post #873 of Old 10-08-2010, 07:01 AM
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Assuming the CPS units are available what if you just replace the unit every 25,000 miles? $150 every few years wouldn't be so bad.

Current: 2005 Wrangler Unlimited - Past: 90 and 92 Trackers and 98 Wrangler SE
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post #874 of Old 10-08-2010, 07:05 AM
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About the Shell Rotella, the formula changed a while ago. It doesn't have enough ZDDP in it anymore. Not for the past 3-4 years.

'98 Sahara w/AX15 & 4.6L stroker, 2.5" OME lift, 32" BFG M/T's, 8.8 w/Detroit Trutracs & 4.10's F&R
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post #875 of Old 10-08-2010, 07:32 AM
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Quote:
Originally Posted by keithert View Post
Assuming the CPS units are available what if you just replace the unit every 25,000 miles? $150 every few years wouldn't be so bad.
Are they now available? I dont know, I havent taken my Jeep apart, that is coming up this weekend. I went from a few seconds of "Screaming Monkeys" to 0 oil pressure last weekend. I imediately turned it off and towed it home.

I have never been in a Jeep engine before, how bad is the camshaft going to be to replace?


PS My local dealer told me "You are out of warranty, Chrysler isnt going to help".
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post #876 of Old 10-08-2010, 07:40 AM
steamnsteel
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Quote:
Originally Posted by SkylinesSuck View Post
About the Shell Rotella, the formula changed a while ago. It doesn't have enough ZDDP in it anymore. Not for the past 3-4 years.
I spoke with a Shell rep. and yes the formula has changed, but it is still 1100ppm which is enough for gas flat tappet. The best I remember the original mix was 1600ppm and they had to lower it for the new diesel epa requirements.
All of my flat tappet engines are now filled with Rotella and the jeeps like it, no more clicky, clicky on cold starts.

2006 LJ Rubicon 6 speed: Currie arms, Currie Track Bars (They don't hit either), Nth tuck, Nth Springs and oil pan skid, JKS mml, bml, Antirock.

I un-insatalled the wife mod.....lost one Jeep.
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post #877 of Old 10-08-2010, 07:46 AM
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Quote:
Originally Posted by B_faster View Post
Are they now available? I dont know, I havent taken my Jeep apart, that is coming up this weekend. I went from a few seconds of "Screaming Monkeys" to 0 oil pressure last weekend. I imediately turned it off and towed it home.

I have never been in a Jeep engine before, how bad is the camshaft going to be to replace?


PS My local dealer told me "You are out of warranty, Chrysler isnt going to help".

Just ordered mine this week. Got a shipping confirmation this morning from moparonlineparts.com. With all the replies I read here about backorders (from a couple of months ago), I hope I ordered the right part since mine shipped so quickly!

Haven't pulled my existing OPDA yet. Just wanted to get my hands on one in case I need it. Mine is a REV-E, but my build date is MARCH 05, just outside the official TSB date range (I think).

Does my build date seem too early for a REV-E part?
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post #878 of Old 10-08-2010, 08:19 AM
DstroyrOfWrldz
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Quote:
Originally Posted by keithert View Post
Assuming the CPS units are available what if you just replace the unit every 25,000 miles? $150 every few years wouldn't be so bad.
I would still do whatever you can with the high quality ZDDP oils to try to make sure they last 25,000 miles; since there have been accounts of failures before 20k.

I'm going to buy one, have it fitted with the old gear, install a grease zerk for the upper bushing, and take it to machine shop to have an oil groove machined onto the shaft for the lower bushing. That may seem more extreme than just replacing it periodically but there's just something in my personality that won't let me accept 25k replacements for something that should not even come close to wearing out before a set of tires.

Joe
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post #879 of Old 10-08-2010, 11:24 AM
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What are the common oil pressure designators? My 2005 only has dots to mark oil pressure. I'm at just past the center toward high with a fresh batch of 5w-30.
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post #880 of Old 10-08-2010, 02:52 PM
DstroyrOfWrldz
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Originally Posted by willydigger View Post
What are the common oil pressure designators? My 2005 only has dots to mark oil pressure. I'm at just past the center toward high with a fresh batch of 5w-30.
my understanding is that the oil pressure gauge is nothing more than a glorified idiot light. It's actually run by the computer to show in the normal range unless the oil pressure falls below that which is required to activate a minimum pressure switch - at which point the gauge drops to zero.

It's become increasingly common across several manufacturers to do this. The idea is that it reduces the burden of unnecessary visits to the dealer service department that arise from ignorant owners panicking when they see the oil pressure rise and fall as is normal with changes in RPM and temperature.

I know for a fact Ford does this, and I had a Mazda that even did the same thing with the coolant temp gauge.

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post #881 of Old 10-08-2010, 03:00 PM
steamnsteel
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Quote:
Originally Posted by willydigger View Post
What are the common oil pressure designators? My 2005 only has dots to mark oil pressure. I'm at just past the center toward high with a fresh batch of 5w-30.
I am thinking that your oil pressure will read pretty much normal until the actual pressure drops to about 6 psi. I am n ot certain but this is the number that comes to mind. And yes it is nothing more than a glorified idiot light.

2006 LJ Rubicon 6 speed: Currie arms, Currie Track Bars (They don't hit either), Nth tuck, Nth Springs and oil pan skid, JKS mml, bml, Antirock.

I un-insatalled the wife mod.....lost one Jeep.
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post #882 of Old 10-08-2010, 05:29 PM
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I was told something was broke in my transmission after about a week, then the dealership told me that it would not be covered since I have a lift kit on. I have a 4" Fabtech suspension lift, does this seem like something legit?

I called up Chrysler and am waiting for them
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post #883 of Old 10-08-2010, 05:47 PM
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The above posters are correct. The oil pressure gage is just for looks. The oil pressure switch makes contact at a low pressure, something like 5 or 7 psi. The computer moves the oil pressure gage, including lowering the pressure at idle, just to make us happy. The gage reading has nothing to do with reality. This has been confirmed by the "good tech" at the dealership.

At least Jeep was smart enough to make the gage move. My Ford Power Stroke Diesel, was either at 0 or right in the middle, no other movement, but the same idea, still not reality.

Jean - Wonderful wife
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post #884 of Old 10-08-2010, 07:55 PM
SkylinesSuck
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Well the oil pressure gages in the newer model TJ's must have changed then. My '98 has an actual pressure gage that varies with rpm/temp/oil weight (when I change it of course.) It may not always be the most accurate in the world. I've had them read low however, then changed out the sender, and it was fine. I have compared it to a mechanical gage and when it was correctly, it was pretty accurate and certainly not an idiot light. Again, this is on a '98 though.

'98 Sahara w/AX15 & 4.6L stroker, 2.5" OME lift, 32" BFG M/T's, 8.8 w/Detroit Trutracs & 4.10's F&R
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post #885 of Old 10-08-2010, 07:59 PM
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Yeah, they changed them. If you have PSI markings, you have a real one. Idiot light one has no numbers.

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