Aftermarket 3.6 Engine Oil Cooler?

[Hootbro]

Good Deal. I think I'm going to increase the oil change intervals and let it ride. I appreocate the feedback. GH

If you really want to know the gnats ass details to see if your oil is holding up, I highly recommend doing oil analysis sampling.

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[Jaybre007]

Don't try to keep it below 3,000 - that's a mistake. Yes, I let mine wind up to 4300 routinely. Yes, it helps and runs cooler.
If you think you are trying to save it keeping the RPM down too low - you are making it struggle and it will run hotter. These need to wind up. It's how modern gas engines are.
You are making less power and torque at lower RPM and making it struggle to haul the same load at the same speed - while restricting it.
Let 'er rip. Seriously.
You'll do harm if you try to keep it down under 2500-3,000 if it's a hard pull.

Well now I just learned me something. Thanks for this posting. I thought I was saving gas because the rpm’s were too high for too long but i see your point. Again, thanks.

 

[ShadowsPapa]

Well now I just learned me something. Thanks for this posting. I thought I was saving gas because the rpm’s were too high for too long but i see your point. Again, thanks.

The design of the engine and original programming was that the VVL would keep the intake valve lift on the low side and a larger LSA for smooth idle and low speed performance until you hit 2800 RPM.
(maybe Charles can verify if it's STILL that way - some say that these never run on low lift but that's hard to believe from cam wear I've seen. I've been told that FCA scrapped the original VVL operation because people complained they could feel the transition - I find that tough to believe but then it could be true. )
Anyway, if it's true to the original programming, the engine is never using what it's got until you are at least close to 3,000 RPM. Then it's in high lift mode, breathing in the air and producing more power.
If you want power you increase valve lift and duration as much as possible - without getting the LSA too small and causing rough idle and low vacuum.

 

[ChrisNLA]

Temps were in the low 80's, but altitude wasn't much in the Appalachains, under 4,000 feet. I do tend to shift manually just to prevent the engine racing. It doesn't seem to hunt, it just doesn't shift early enough for my taste. I don't think it needs to be in the 4500-5000 RPM range to keep power.

Peak torque in these little guys is right around 4,400 RPM, horsepower at about 6,350 - they lgotta spin.

Actually. This had me wondering and so I checked - even the 'great big' 6.2L V8 in my SS Camaro....peak torque is at 4,300 RPM with HP at 5,900. I took it to a high performance track day last summer and beat it on a 2.5 mile road course for a couple sessions. Saw engine oil temps in the 260's - with 8 quarts of coil to spread the heat around in as well as an external cooler.

Like the others said - not a big concern. Let the engine work some and adjust the oil change window to suit. Getting Blackstone analysis on one of those oil changes would be fun too. See how it held up.

 

[ShadowsPapa]

Getting Blackstone analysis on one of those oil changes would be fun too. See how it held up.

Beat me to it.

I recall the first time I towed with my Silverado equipped with the LS engine on the hills of I80 east. I hit one of those inclined and holy bat guano Batman, that thing dropped back a couple of gears and the tach shot up to around 5,000 RPM and I was WT........... - what's up with this? The whole trip it saw 4,000+ RPM on the hills, 3,000s weren't uncommon at all. It really wound up, almost never dropped into the low 2,000s or below unless on a flat or down hill.
Got back and talked to the sales guy - he was with one of the other Chevy truck LS owners who towed a huge big tall heavy boat behind his and they both laughed.
Get used to it, they said - these engines are happy there. And they reminded me of how the LS engines sound at the track, hitting those RPMs for long stretches' never breaking a sweat.
Then when I got my JT and towed, I saw that it also needed to wind up but not as high as the LS engine did, and it seemed happy there as well.

 

[smlobx]

Not wanting to derail the OP’s thread but you may want to consider running a slightly heavier synthetic oil like 5W-30 or 0W-30.

I realize this is not what the bean counters at Jeep designated to be able to get 0.001% more mileage out of the truck but there is some evidence that a slightly heavier oil will help …

 

[Tom C]

Just a stupid question from someone who doesn’t know squat. If you aren’t going off roading for a long period of time, would removing the front skid plate help airflow and cooling?

 

[ShadowsPapa]

Not wanting to derail the OP’s thread but you may want to consider running a slightly heavier synthetic oil like 5W-30 or 0W-30.

I realize this is not what the bean counters at Jeep designated to be able to get 0.001% more mileage out of the truck but there is some evidence that a slightly heavier oil will help …

Heavier oil moves more slowly and gets hotter, not cooler. Engineers have proven that. The weight of the oil isn't a problem. Also more shear forces involved causing potential elevated oil temperatures in the bearing areas. As long as there is oil there, viscosity won't protect it better. And he made no mention of low pressure - and he shouldn't see low pressure because they are pretty high volume pumps.

 

[ShadowsPapa]

Just a stupid question from someone who doesn’t know squat. If you aren’t going off roading for a long period of time, would removing the front skid plate help airflow and cooling?

No, it could cause more drag and thus more load on the engine. Air flow needs to go through the radiator, not up from under and around it.
the skid plate if equipped, and the air dam if no skid plate help reduce drag, engine load and move air where it needs to go.

If such a thing mattered, they'd not have the air dam on the Sport and Overland models - remember they did everything they possibly could for cooling to meet the tow numbers. Any mods will take that backwards.

 

[Charles 236]

The design of the engine and original programming was that the VVL would keep the intake valve lift on the low side and a larger LSA for smooth idle and low speed performance until you hit 2800 RPM.
(maybe Charles can verify if it's STILL that way - some say that these never run on low lift but that's hard to believe from cam wear I've seen. I've been told that FCA scrapped the original VVL operation because people complained they could feel the transition - I find that tough to believe but then it could be true. )
Anyway, if it's true to the original programming, the engine is never using what it's got until you are at least close to 3,000 RPM. Then it's in high lift mode, breathing in the air and producing more power.
If you want power you increase valve lift and duration as much as possible - without getting the LSA too small and causing rough idle and low vacuum.

These engines start in high lift and immediately switch to low lift. They have to start in high lift because they require oil pressure to switch to low lift. Just looking at the high lift arms of the intake rockers will show minimal wear, because the rockers are always going to run on the high lift lobes at start up. As far as the point at which the high lift rockers are engaged when running, I don't know the exact RPMs where the switch from low to high lift is, but I do believe that it is somewhere around 2,800 to 3,000 RPMs. I have probably read the actual number in the technical data, but I don't remember because I don't need to know where the switch is, but if it is switching properly. It is a seamless transition when it is working properly.

 

[ShadowsPapa]

These engines start in high lift and immediately switch to low lift. They have to start in high lift because they require oil pressure to switch to low lift.

Makes total sense, thanks. And of course the positive side effect is a valve open more for starting.
I had trouble with the idea of these being reprogrammed to run always in high lift because of complaints. They'd lose some of the MPG advantage in town driving.

 

[Gregors]

As always you guys are and amazing wealth of information. I appreciate the insight!

 

[Charles 236]

Makes total sense, thanks. And of course the positive side effect is a valve open more for starting.
I had trouble with the idea of these being reprogrammed to run always in high lift because of complaints. They'd lose some of the MPG advantage in town driving.

Also, as you noted above, in high lift there is more valve overlap causing a rougher idle and loss of low speed torque. I have taken apart some of these engines that have considerable mileage and, based on observed wear on the high lift arms and lobes, can only conclude that the engine was driven at RPM levels that never required high lift.

These engines really come to life at high RPMs. The classic Pentastar without VVL definitely has the old school, "getting up on the cam" feel that the old supercar engines had with a high lift, high overlap cam. Kinda makes me think how great a PUG would run if the high lift was really aggressive, instead of being relatively mild.

Also, these engines have a pretty good oiling system, the oil pick up tube is about an inch in internal diameter and the pump has so much volume capacity that it uses a variable volume system to cut down on power lost to drive the pump. Actual bottom end failure is almost unknown, and if the Internet didn't keep overstating the cam wear issues (statistically rare), people would probably like the Pentastar a lot more.

 

[ShadowsPapa]

Also, as you noted above, in high lift there is more valve overlap causing a rougher idle and loss of low speed torque. I have taken apart some of these engines that have considerable mileage and, based on observed wear on the high lift arms and lobes, can only conclude that the engine was driven at RPM levels that never required high lift.

These engines really come to life at high RPMs. The classic Pentastar without VVL definitely has the old school, "getting up on the cam" feel that the old supercar engines had with a high lift, high overlap cam. Kinda makes me think how great a PUG would run if the high lift was really aggressive, instead of being relatively mild.

Also, these engines have a pretty good oiling system, the oil pick up tube is about an inch in internal diameter and the pump has so much volume capacity that it uses a variable volume system to cut down on power lost to drive the pump. Actual bottom end failure is almost unknown, and if the Internet didn't keep overstating the cam wear issues (statistically rare), people would probably like the Pentastar a lot more.

LOL - sorry, gotta laugh, as you've confirmed some of the stuff I've talked about like that pump being a high volume pump, for example. Compared to the pumps in other engines driven off the cam at half engine RPM that thing will move a lot of oil in a short time. And a 1" pickup tube is a lot larger than most others. Of course it has to be high volume for the phasers, VVT needs, all of the oil squirters for cams and followers and such, but still.........

Since I wanted to use the stock MAP and stock PCM with the 4.0 in my car I had to watch the LSA and lift. I went as rad as I could but still keep the idle sooth and vacuum up (everything about that car needs vacuum - brakes, HVAC, 4x4 shift system and so on)
My other car, I don't care - makes enough vacuum for the brakes most of the time.

I'd wondered about the valve train seeing photos of some of the tear downs. Didn't look like it wasn't running on the low lift rollers all the time. Some, though, look like they were stuck on high lift all the time.

As always you guys are and amazing wealth of information. I appreciate the insight!

It's what some of us have done for decades. I made my money at it, used it to get me through life, and I've been extremely fortunate and lucky in most of my life, time to give back some of that education and experience. (and looking at my shop, time to start giving away other stuff, too!)

 

[troverman]

Heavier oil moves more slowly and gets hotter, not cooler. Engineers have proven that. The weight of the oil isn't a problem. Also more shear forces involved causing potential elevated oil temperatures in the bearing areas. As long as there is oil there, viscosity won't protect it better. And he made no mention of low pressure - and he shouldn't see low pressure because they are pretty high volume pumps.

Not sure I can agree. Air-cooled Harley-Davidsons use 20w50 motor oil, because the heavier oil can handle the higher heat those engines see. Likewise, heavy duty diesel engines use 15w40 for similar reasons. Very light oils, like the 0w20 the Pentastar wants, are great for less wear on very cold starts, they crank easier, and they get better fuel economy. However, they tend not to protect metal as well.

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