RTS SM/CJ 5w40, Jeep 4.0, 5726 miles

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440Magnum

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The interesting thing here (other than the fact that 4.0s rock on RTS... zero make-up oil by the way) is the comparison between this analysis, which was RTS SM/CJ, compared to the previous analysis which was RTS SL/CI4 About the only difference is the Mg/Ca ratio, as I suspected. Zn/P is STILL > 1000 PPM in RTS SM/CJ (at least pre-T6), so don't believe people when they say its not!

The current fill went back to SL/CI4 (burning through stock). Next summer I plan on giving it a fill of T6. Oil filter was a Pure One, upsized to a PL3001 instead of the stock skinny filter.

Did I mention that Jeep 4.0s continue to just blow me away?

JeepOil12_09.jpg
 
I forgot to mention that although this Jeep Cherokee is "my daughter's" (my name's on the title) for her daily commute to school, we also take it out to West Texas most years. Both of these analyses include a run out to the Guadalupe Mtns and Davis Mtns, HEAVILY loaded, and with that wonderful 250+ mile stretch of 80+mph on I-10. With the car-top carrier and headwind, its darn near WOT for several hours. That 4.0 just doesn't mind.
 
Originally Posted By: Troy_Built
BTW, don't it make you feel better knowing your daughter has a nice safe car to drive?


That was the whole reason I bought the Cherokee (well, that and the fact that I've known its history since the first owner bought it new- we work together). What I didn't expect was how much I would fall in love with the truck during the year I had it before my daughter got her license and I handed her the keys. I really missed out on never owning a Cherokee from new- they're just incredible, simple, nice-driving (even though they're solid axle) utterly reliable little trucks.
 
Interesting to see how the newer RTS held it's viscosity a bit better than the old one, even with a longer interval. Apparantly, one of the other changes they made to CJ/SM version was an improved VII.....seems to be working.

This one could have comfortably done about 7-8k....any plans to extend OCI?
 
Originally Posted By: addyguy
Interesting to see how the newer RTS held it's viscosity a bit better than the old one, even with a longer interval. Apparantly, one of the other changes they made to CJ/SM version was an improved VII.....seems to be working.

This one could have comfortably done about 7-8k....any plans to extend OCI?


Based on miles alone I've got no problem pushing it out a good bit further. On the other hand, I'm only changing the oil 2x per year at a 6k interval, so its not like I really need to do so. But yeah, I figure I'll let it go closer to 8k next time.
 
Fantastic oil. Fantastic engine. Great comparison between SL and SM.

Love how they switched from calcium to magnesium. Keep an eye on the things that can kill an awesome running engine at that age (head gasket leaks, other gasket failures, and intake failures). As long as they either don't pop up or are addressed quickly, this thing will hit 300-400k.

Your post, seriously, made me realize how much I've always wanted one of these as a beater. I had a Jeep Wrangler 4.0 5-speed, and I think the "extras" of the Cherokee would be the right blend for what I'm looking for....
 
Btw Magnum - How's the 5-speed transmission in that rig holding up? Original clutch? I can't remember how robust the overall setup and invididual components were (i.e. TO bearing, clutch, etc.)
 
Originally Posted By: JoeFromPA
Btw Magnum - How's the 5-speed transmission in that rig holding up? Original clutch? I can't remember how robust the overall setup and invididual components were (i.e. TO bearing, clutch, etc.)


Hi Joe,

I love 5-speeds, but frankly the one used in pre-2000 Cherokees isn't all that great (Aisin AX-15). It is better than the AX-5 and a Pugeot that Jeep used in the 80s, though. My main gripe with it is that they changed the synchros in about 1996 so that it REQUIRES GL-3 oil, just as GL-3 oil was becoming unobtainium. It also needs a 90-wt oil, so you can't use ATF. I tried Redline MT-90 (GL-4, about the safest gear oil I could find) and within a few months started getting blocked shifts to first gear and other synchro quirks. I went to a Chrysler dealer service department and basically said, "Ok, smart guys, what do YOU use in one of these when it comes in for service?" They pulled their supercede list and TSBs and showed me a paper trail where Chrysler engineers recommend 10w40 synthetic engine oil for the AX-15. So I tried that, and darned if it isn't working well again.

That said, its actually a pretty nice-shifting unit, and seems to go a long time without trouble for the average driver. Just not super beefy and I gather it sometimes fails in harder offroading. It has your typical Japanese truck transmission super-noisy reverse gear, also. In 2000, Chrysler switched the Cherokees to the New Venture Gear NV-3550 for the last 2 years of production (and its also used in Wranglers IIRC). MUCH tougher transmission, uses ATF IIRC.

Mine had a clutch/throwout bearing replacement at ~60,000 miles (previous owner) because the rear frost plug was leaking coolant and the transmission had to come out anyway. So as of now my clutch "only" has about 75k miles on it. So far so good. The previous owner had a 93 Cherokee with an AX-15 prior to this one, and its clutch was still going fine when he sold it with around 130k miles.
 
Great info. I'd pick up ~ 2001 model or so if I ever did honestly. I like final model year runs when picking up used cars, so it's good to know it would have the tougher trans and hopefully a bit nicer shifting.

I rememeber the 5-speed in my 97 Wrangler Sahara 4.0. Long throws and vague action, but [censored] if that thing wasn't easy as cake to drive and near impossible to screw something up as I remember it. Yeah, revese gear was super noisy. No big deal to me (funny you mention Japanese, I never put 2+2 together but reverse is super noisy on my 2006 Civic SI, 2008 Subaru Legacy GT, and my 97 Wrangler. Don't remember it being noisy on my 1994 Eagle Talon 5-speed though).
 
Originally Posted By: JoeFromPA
Great info. I'd pick up ~ 2001 model or so if I ever did honestly. I like final model year runs when picking up used cars, so it's good to know it would have the tougher trans and hopefully a bit nicer shifting.


Well, there's a DIFFERENT gotcha with the 2000 models. They changed the cylinder head casting to add mounting points for the coil-on-plug ignition rail (1999 and prior has a distributor) and they also revised other parts of the casting.... and these heads are somewhat prone to cracking (the casting number includes "0331" so they're called the "331" head). It seems that if they're going to crack, they do so by 80k miles or so. They fixed it either mid-year 2000 or 2001. Generally the 1999 and 2001s models are considered the "best" all-around Cherokees. But they're all good.


Originally Posted By: JoeFromPA
I rememeber the 5-speed in my 97 Wrangler Sahara 4.0. Long throws and vague action, but [censored] if that thing wasn't easy as cake to drive and near impossible to screw something up as I remember it. Yeah, revese gear was super noisy. No big deal to me (funny you mention Japanese, I never put 2+2 together but reverse is super noisy on my 2006 Civic SI, 2008 Subaru Legacy GT, and my 97 Wrangler. Don't remember it being noisy on my 1994 Eagle Talon 5-speed though).



The Aisin tranny is closely related to Toyota transmissions (Aisin is partially owned by Toyota). The reverse sound is one I always associate with 80s Toyota compact trucks, not so much cars. And the shifter feel is pretty much the same as those compact trucks too- not sporty, but its very easy to operate and hard to get the wrong gear or miss a gear in spite of the vague feel.

I don't know that the NV3550 really shifts "better," but its definitely stronger internally.
 
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My main gripe with it is that they changed the synchros in about 1996 so that it REQUIRES GL-3 oil, just as GL-3 oil was becoming unobtainium.


Yeah. The dealer is the only source for the synthetic GL3 fluid. It's not just some rebadged domestic product. I know of no other GL3 fluid available in North America. That said, The lighter MT rated fluids work well. Even the OEM fluid will still give you a notch 1-2 engagement if you're in a hurry in sub freezing temps.


Good showing on the RTS. I'm kinda surprised that the TBN degraded that low in about 6 months. This should be good for a full year under most conditions; at least in that regard. It sure kept the Fe gremlins of the distant past in check.
 
Had a '91 F150 with the 300/6 and the Mazda/Ford M5OD2 5-speed and it used ATF(!) but a quality 10W-40 synthetic (AMSOIL) with the addition of the Ford Limited Slip Diff additive really smoothed things out for me.

Cheers!
 
Originally Posted By: Norm Olt
Had a '91 F150 with the 300/6 and the Mazda/Ford M5OD2 5-speed and it used ATF(!) but a quality 10W-40 synthetic (AMSOIL) with the addition of the Ford Limited Slip Diff additive really smoothed things out for me.

Cheers!


Limited slip additive in the MANUAL TRANSMISSION?!?!? That's usually the absolute worst thing you can do to synchros! Not necessarily destructive (unless they use copper-containing metal that is attacked by the sulfur additives, as is the case in the Aisin transmission) but LS additive tends to keep the synchros from "grabbing" quickly. That's what its supposed to do in order to prevent LSDs from "chattering."
 
Originally Posted By: 440Magnum
Originally Posted By: Norm Olt
Had a '91 F150 with the 300/6 and the Mazda/Ford M5OD2 5-speed and it used ATF(!) but a quality 10W-40 synthetic (AMSOIL) with the addition of the Ford Limited Slip Diff additive really smoothed things out for me.

Cheers!


Limited slip additive in the MANUAL TRANSMISSION?!?!? That's usually the absolute worst thing you can do to synchros! Not necessarily destructive (unless they use copper-containing metal that is attacked by the sulfur additives, as is the case in the Aisin transmission) but LS additive tends to keep the synchros from "grabbing" quickly. That's what its supposed to do in order to prevent LSDs from "chattering."


Worked like a charm in that application: the guy that bought the truck from me in 1999 drove it for another 100K miles and then gave it to his son... I'm sure he never touched the tranny or I'd have HEARD all about it from him!

Cheers!
 
My daughter's Cherokee 4.0 4X4 has 180000 miles -- No leaks, uses no oil, runs excellent. She's out at Tx Tech and drives home several times a month. When we had 12" of snow in Dec. It was the only car we drove and we have several much newer.
 
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