playbass

I can chime in with agreement. I ran Royal Purple last winter for one cycle and then did a Used Oil Analysis after 3000 miles. It wasn't good, the oil looked to have been run over 5 miles and was no longer at w30 but lower.

I ran a cycle with Mobil 1 High Mileage and got a clean bill of health on the next UOA after 3000 miles. The analysis said it could have been ran a lot longer, such as 5-6k miles. I've been using this the last 2 OCI since that report. I do think the Mobil 1 HM increased the engine clatter a tad over Castrol HM (which I used to use but never had analysis done on.)

salad

Good question. Technically the answer is "not too worried". The big reason for low zinc levels in API SN oils is for cat life, sure, but the detrimental effects to flat-tappet engines like ours outweigh the savings by using SN oils.

The following article discusses the introduction of API SM and what it means for our older engines:
http://www.allpar.com/old/oils.php

Okay, great. So we've covered lower ZDDP levels with some molybdenum additives. Of course, results are mixed on the effectiveness, but SM was generally well received.

Of course a few years ago SN was introduced which changed a number of requirements and limits quite a bit. Here's a rundown on what happened and why this is a problem. Note the Ford camshaft of a similar design to our 4.0s that's been wiped by using new SN-rated oil: http://www.aa1car.com/library/api_mo...ifications.htm

So that's "new" motor oil. What about the older stuff? What were our Jeeps designed to run on?

Over time the API develops and publishes new standards for lubrication. (see http://www.api.org/certifications/en..._march2010.pdf for a basic list.) With each revision there are usually modifications to additives, flow rates, shear stability, seal conditioning, etc. In addition to introducing new technologies, changes are also made to accommodate regulatory requirements (EPA mandates), and design changes in equipment. For example, new engines do not use flat-tappet cams. Likewise, the current API GL-5 gear oil is almost exclusively designed for hypoid gears and will destroy any transmission with brass synchronizer rings. This is important to keep in mind as "newer" is not necessarily "better".

While our engines have ancestry back to when API SC was current, the 4.0L was designed and introduced during SF. It saw some minor tweaks during the few generations and was sold under the lubrication standards of SF, SG, SH, and SJ. I find it's safe to assume that the engine is essentially optimized for the additive packages contained in those year ranges (1979-2001).

So what's the difference in zinc? Shamelessly stolen from http://www.bobistheoilguy.com/forums...71&type=thread

Grade Zinc, Phos
SM MAX 800
SL/SJ 1000-1400
SH 1000-1400
SG 1000-1400
SF 1000-1400
SE 1000-1200
SD 1000-1200
SC 1000-1200
SB 1000
SA 0

The low maximum for API SM can be explained by our article at AllPar, as well those classifications really apply to xW20 and xW30 oils. There are actually different rules for xW40s, which includes our diesel oils like Rotella, Delvac, Delo, and so on.

Let's compare some current oils:

5w30 Mobil 1 (API SN): ~800 ppm zinc content
5w30 Pennzoil Ultra (API SM): ~800 ppm zinc content
5W50 Motorcraft (API SN): ~600 ppm (!!!) zinc content
5W30 Castrol GTX (API SN): ~800 ppm zinc content

5w40 Shell Rotella T6 (API SM - SH, CJ-4, CI-4, etc): ~1300-1500 ppm zinc content
15w40 Mobil Delvac (API SM - SH, CJ-4, CI-4, etc): ~1300 ppm zinc content
5w40 Mobil Delvac 1 ESP (API SM - SH, CJ-4, CI-4, etc): ~1300-1500 ppm zinc content

Huge difference! As you can see from all the information above, the additive packages in modern HD diesel oils provide at least the same amount ZDDP as what the 4.0L was designed for, and even more protection by meeting API SM's requirements for molybdenum anti-wear additives.

With all this in mind, I feel confident in concluding that the longest life in a 4.0L will be achieved with high zinc levels, and used oil analysis with HD diesel oils show consistently that 5W40s result in the least amount of engine wear. My primary concern is reliability, so this really matters to me.

However, to answer what you asked in the first place (lol), the catalytic converters were designed to last with high ZDDP levels in the first place. I rarely see people requiring to replace their cats, and consider yours lasted about 12 years, which I consider abnormal. With the mini-cats only being worth about $200 each (RockAuto.com), that's much less than having to replace your cam in a similar time frame due to premature scuffing.

Remember, the diesel oils have no more zinc than what these vehicles were designed with, so I would not expect any accelerated wear. Keep your oil consumption in check (piston rings, valve seals) and you should be fine.

skife

It's a 4.0 change the oil once in awhile, it'll run forever.

peelman

Just picked up 5L jug of Rotella 6 0w40. Should good for the cold weather coming soon. I normally find Rotella 6 5w40 or 15w40 in stores.

sgjii

Thanks Salad.

I for one, truly appreciated the details and strive to understand "Why?"

Sometimes I go into great detail and get chastised for it but I think it is important to convey an understanding not just an answer.

One colleague likes to tell me "I just want the Baby, not the whole Pregnancy." LOL

sgjii

Regarding oil, I was recently told that the Tractor Supply house brand of oil called Traveller® Premium All Fleet Diesel Engine Oil, is re-labeled Shell Rotella T dinosaur oil.

I tried the "Google Machine" to see if I could find supporting data but beyond couple of Ford & GM Diesel Forum posts that state it, nothing concrete.

It is currently on sale and I have seen it on sale more than once, for only $8.99/gal which is a good deal compared to my local price of $13.99 for a gallon of Rotella.
http://www.tractorsupply.com/en/stor...gine-oil-1-gal

Comparing Salad's data regarding specs (SG, SH, CJ-4, CI-4, etc.) if it is not actually Rotella re-badged, could still be a nice choice.

ksrummel

So Rotella 5w40 would be a good winter choice or 5w30 ?

salad

No problem, glad you liked it lol. I'm the same way. A lot of that was research for me too, I didn't realize that today's diesel oils have the same ZDDP as yesterday's gasoline oils.

Yeah that's probably rebadged Rotella. Note the list of certifications... you think a junk in-house brand is going to shell out for all that testing? Meets API SM and CJ4 in a 40 weight so I wouldn't hesitate to run it. Well, except 15w40 is pretty thick juice for winter.

Yes

Parsnip

Yea, what fool would run 15w 40 in cold weather like the upper 20s low 30s, surely no one
>.>
<.<
Yea I have dino oil in it now...but hey man, 40 psi on my 300k mile motor at ot, I'm cool with it

DieselDaze

no reason for shame here bro, you had to geek out on that oil jargon from somewhere...

ksrummel

And try to go for a synthetic blend or straight synthetic?

PocketsEmpty

After reading many of these oil debates I've decided to stick with the Napa GOLD / WIX filters and switching to Rotella T6 5w40 next change

salad

Whatever you like... synthetic is so cheap in the USA I think you guys are nuts for not running it in the first place (generally our oil on sale up here is still more expensive than for you guys) but it comes down to preference and budget. There are many fine diesel oils in conventional, blend, and full syn. Keep in mind that just because you run a synthetic doesn't mean you get giant oil changes intervals like 10k miles. The biggest problem on old gas engines is that fuel slips by the rings on the compression stroke and dilutes the oil, thinning it out below what the engine needs. This is a major reason that city driving is considered "severe service" and the OCI is decreased to like 3k miles.

I buy into the magic hand-waving that synthetic is better and don't mind blowing the cash on full syn. But if you're on a budget and change oil frequently it doesn't make as much sense.

If you really want to geek out check this: http://www.ihpartsamerica.com/forums...filters-2.html

sgjii

Now THAT is "Pregnancy Level Detail"!!!

To summarize for those that don't want to read the entire post, the best oil filter for your IH V8 Gas engine is the Baldwin B7311-MPG

PocketsEmpty

Wow. That guy has some serious free time on his hands.

Salad, how often do you change your XJ oil? Yours is a DD right? I'm thinking I can go 6k with the synthetic, and that will take me over a year to reach probably. Maybe I should just change it once a year since it isn't my daily.