1998 Jeep Grand Cherokee Laredo 4.0L

[Pablo]

OCI = oil change interval - you answered it!

Well I guess we can now rule out the air filter

previous 5k with K&N = 16ppm
next 7k with Amsoil = 22ppm

I have to run now...more later sorry.

PS Sorry for being snappy before.

 

[Pablo]

Allow me to continue.

Perhaps I was wrong on the cleaning - comment. It certainly is possible that some cleaning from the early dino oils continues - but the oil certainly isn't overly oxidized.

Let's dismiss the Si as a causitive factor. The Na while seemingly high vs. virgin ATM/ASL may not mean much...B (Boron) may seem strange, but it's an additive and to some extent the Na may tag along.

So the only thing I can really speculate is that there is some "issue" at your bearing journals - be it excessive wear from the age of the design or machining/assembly tolerances I do not know. It's not killing the oil - but the oil is not completely preventing this accelerated wear.

I would say - compare to other UOA's, do a double Auto-Rx flush, try a shorter OCI, try an oil with a different AW package - high Mo perhaps(Redline?)

[ May 16, 2003, 10:59 AM: Message edited by: Pablo ]

 

[MolaKule]

jeepzj,


I recently discarded my Amsoil 2-Stage air filter after having high iron, lead, and aluminum readings from the UOA in my Chev. 350 V8. I had cleaned the filter every 15,000 miles and reoiled.

I switched to a paper air filter. The wear readings are down and the oil doesn't turn dark as soon now, as when the Amsoil 2-stage was installed. It was theorized that the foam 2-stages have pores that open up with time and allow dirt to pass through.

My recommendation, ditch the Amsoil 2-Stage and use a paper-type filter for the next UOA interval.

 

[jeepzj]

MolaKule, maybe I should leave the Amsoil 2-stage in for my next UOA with the 10W30 and see if it makes any difference. If it doesn't improve then I still have the K&N filter which I will probably try for another UOA. If it still doesn't improve then I will go back to paper filters. What's a good paper filter that's realtively inexpeensive? Stick with OEM?

 

[Bror Jace]

Hmmm ... with a low tech (and low RPM) engine, is synthetic oil really needed here?

I'd love to see what Schaeffer 7000 10W30 would do in this engine. It seems like it could use the extra barrier protection with all those surfaces rubbing against each other.

--- Bror Jace

 

[Patman]

quote:

---

Originally posted by jeepzj:
What's a good paper filter that's realtively inexpeensive?

---

Fram.

My wife's 5000 mile analysis last year showed only 4ppm of silicon, using a Fram air filter.

 

[msparks]

quote:

---

Originally posted by jeepzj:
MolaKule, maybe I should leave the Amsoil 2-stage in for my next UOA with the 10W30 and see if it makes any difference.

---

That sounds like a good plan. I would be that your short trips, 80% city are the cause for the High Lead, same goes for the Iron. I would say if the SI is consistant, the it's not the air filter, if it was the airfilter, it would be getting worse the longer you ran it.

Also not just the air filter, but the whole intake, all hoses secure, any vacuum leaks could suck in dirt as well. Make sure your dipstick tub is in good shape as well as your oil fill cap. Dirt can get in from anywhere.

 

[MolaKule]

jeepzj,

Sounds like a good plan, what Msparks said.

Also check the air intake and PCV grommets on the valve covers. I have found that these can also contribute to air leaks affecting silicon readings. And speaking of valve covers, make sure gaskets are sealing and the covers are torqued down.

 

[Greaser]

quote:

---

Originally posted by Bror Jace:
Hmmm ... with a low tech (and low RPM) engine, is synthetic oil really needed here?

I'd love to see what Schaeffer 7000 10W30 would do in this engine. It seems like it could use the extra barrier protection with all those surfaces rubbing against each other.

--- Bror Jace

---

ARE you making jest of the 4.0L engine..it's been in production since the 60's in one form or another..and is a 250,000 miler running vegatble oil...synthetic is a good choice in any engine...some might disagree..but the added protection of the syn can't hurt any engine IMO.I don't know why he is using 5W-30 in it...when it calls for 10W-30 in the manual...I use a 10W in the winter and mix 4 litres of 10W-30 and 1.7 litres of 15W-50(Mobil) in the summer...going for 400,000

 

[Pablo]

You guys got my juices reflowing on this one....I might think this engine would be better off with something like a 15W-40....

That's my final answer: try the Amsoil Synthetic 15W-40 HD oil.

 

[Greaser]

quote:

---

Originally posted by Pablo:
You guys got my juices reflowing on this one....I might think this engine would be better off with something like a 15W-40....

That's my final answer: try the Amsoil Synthetic 15W-40 HD oil.

---

This make the most sense in this engine in a warm climate...and go back to a quality paper element in the stock airbox set-up.

 

[Bror Jace]

Actually Greaser I wasn't making fun of the engine. However, older motors with a lot of friction surfaces rubbing would be best with an oil featuring a generous barrier additive package.

I'm not sure a synthetic base oil on its own really offers greater protection unless we are talking about extreme heat, extreme cold or extended drains. In other words, without a good additive package, synthetic oils offer no benefits in the short run and under most typical operating conditions.

Anyway, jeepzj, if you were to go with a 15W40, I'd try Pennzoil 15W40 Long Life which has a good dose of moly. Second choice would be Chevron Delo400 based on results I've seen here. On paper, it doesn't look like anything special.

--- Bror Jace

 

[Greaser]

Bror..Correct me if I'm wrong here..but doesn't a synthetic have better shear stability as compared to a dino due to it's chemical make-up?So all those old fashioned parts rubbing to-gether would benefit from a syn as compared to a dino..even at a short drain interval...yes/no?These engines run at 200 degrees so heat is a factor...with heat comes varnish and sludge...especially if any type of slow,off roading,high load/low rpm applications are thrown in the mix.These motors have old roots but don't actually break-in till around 60,000 miles...they are still produced using modern techniques..sorry if I seem a little defensive of the 4.0L but in to-days world of mutiple-valve,mutiple cam/variable valve,mixed alloy engines it is a simple effective beauty that will go down as one of those motors mechanics talk about from a by-gone day...with fondness...mayb I'm just old fashioned but I like simple stuff...less is better in my books...I love to see old tractors from the forties still chugging in the fields..my friend plays with them as a hobby...lately he's been selling them before he has a chance to restore them...they run for years on duct tape and a screwdriver...the 4.0L will be replaced by a dual cam engine with cintered iron camshafts and balance shafts bla-bla...it will go down and be a memory of other great low-reving icons..Ford straight six's,302,351, Chev's Iron Duke,350 early years,Chryco 318,360 ,slant six's...engines with strries attached to them that are always a warm memory in the garage chit-chat...ok..I'm done swinging down memory lane.By the way I run syn in both my Jeeps and don't do an extended drain...don't care about the few bucks I lose in engine oil costs..like I said...I'm going for 400,000k

 

[Bror Jace]

Greaser, regarding the more surface areas rubbing togather, I'm not sure that's enough to significantly increase the amount of shear stress on the oil, especially at lower RPMs. Usually, shear stress doesn't come into play with short durations (3,000 miles or less) even with higher-RPM engines. Only when the intervals climb to 4,000 (street) miles and beyond would I expect to see a difference in oil performance.

I didn't think of the high heat ... but actually I'm not surprised. Especially with older engines in newer cars. They tend to lean 'em out and run the temps higher to make them more efficient and cleaner burning (regarding emissions). However, this can also cause problems in an engine which had always been known as being bulletproof ... cracking in the engine, blown headgaskets and other cantankerousness.

So, this engine may benefit from a synthetic oil ... but I still would like to see how a good synthetic blend like the 7000 Supreme would do with its excellent additive package.

You may have a point about the synthetics for this application but at least part of the jury is still out.

And I agree with you about older workhorse engines. They certainly have their charm but I'm also for updating designs. For example I'm slightly appalled that the Chrysler V10 was made as a pushrod design and I wish GM would come up with an OHC design to replace the smallblock Chevy.

--- Bror Jace

 

[darrenc]

Pablo,

While I had a very good UOA with 10W-30, the 4.0 motor really does seem to like 15W-40. You hit it right on the head.

Darren

 

[jeepzj]

I used 10W30 this time as I stated. Can't wait until my next UOA for the results. I still have the Amsoil foam air filter installed and just checked it yesterday again. Looks brand new except for a few small bugs and you really can't tell how dirty it is because the faom is dark to begin with. Can't be that dirty only after 6.5K miles. I don't plan to clean it until after my next UOA of 6000 miles. That would make it 12K miles on the air filter. I'm going with an STP paper air filter after that for my next UOA to determine which one I should stick to. Probably the paper filter but I'm curious on the comparison.