Maximize 3.6 Reliability

[Dusty Dude]

On average, how often are you draining the can?

It will depend on how well the can works or how much oil vapor your particular engine produces. I would check it at 500 miles initially, and adjust the interval based on what you find.

On my Challenger’s 6.1L V8, I only have to drain it at every oil change, but I have a large reservoir on the can.

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[Jeep Dude]

O.K., you asked about the 3.6 engine. Below is from one of the Engineers that Designed it:

Nice! As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability..... The lighter oil was chosen mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another. A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+. Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings. Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact. Cheers! Kevin PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.

Could somebody please explain to me what this means?

"A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there."

What does hydrodynamic within the context of the timing chain, mechanicaly mean here? Sorry, but my english ain't perfect.

 

[N0Buen0]

This..... I installed an oil catch can from Corsa about 10k miles ago and empty it every oil change. The canister is full of oil and sludge that would find its way back into the intake manifold and valves. I can only imagine how much it's helping with carbon buildup.

 

[AnnDee4444]

Not only does it run worse on high octane but it can hurt the engine. Highly recommend you do some research about it.

OK.

https://www.fueleconomy.gov/feg/octane.shtml

"Will using a higher octane fuel than required improve fuel economy or performance?​

It depends. For most vehicles, higher octane fuel may improve performance and gas mileage and reduce carbon dioxide (CO2) emissions by a few percent during severe duty operation, such as towing a trailer or carrying heavy loads, especially in hot weather. However, under normal driving conditions, you may get little to no benefit.​

​

Why does higher octane fuel cost more?​

The fuel components that boost octane are generally more expensive to produce.​

​

Is higher octane fuel worth the extra cost?​

If your vehicle requires midgrade or premium fuel, absolutely. If your owner's manual says your vehicle doesn't require premium but says that your vehicle will run better on higher octane fuel, it's really up to you. The cost increase is typically higher than the fuel savings. However, lowering CO2 emissions and decreasing petroleum usage by even a small amount may be more important than cost to some consumers."​

 

[Spank]

This..... I installed an oil catch can from Corsa about 10k miles ago and empty it every oil change. The canister is full of oil and sludge that would find its way back into the intake manifold and valves. I can only imagine how much it's helping with carbon buildup.

I just added one of these myself a couple months ago and I'm surprised how quickly that thing fills up. Kinda wish I would've done it sooner.

 

[Yankee1019]

What does hydrodynamic within the context of the timing chain, mechanicaly mean here? Sorry, but my english ain't perfect.

Take this with a huge grain of salt because a may not actually know what I'm talking about but I think this is what he means by hydrodynamic.

Imagine you are riding in a boat and your hand is in the water. At slower speeds your had is being pushed through it however as speed increases, eventually your hand starts to skim across the surface of the water. How does this apply to the timing chain? At slower engine speeds the timing chain is pushing through the engine oil that is lubricating the chain guides so there is physical contact between the chain and the guides. At a certain RPM the chain starts to move fast enough to where is rides across the surface of the lubricating oil and is no longer making direct contact with the guides.

This makes sense to me but could be completely wrong.... ?‍

 

[roaniecowpony]

I figure just find the best oil you can, change it often. Variability of fuels available in the U.S. is a low effect on longevity, IMO. I see nothing wrong harmful with ethanol in the fuel. In fact, it should aid in keeping the carbon buildup low. In the end, though, you can do all the things in this thread and end up with a mechanical failure. Do what's practical for your situation and just enjoy.

 

[jeepingib]

I absolutely love all of the weird conversations about fuel that this forum gets into. The "Top Tier" one is new to me. It makes some sense. All fuel in your area likely comes from one, or possibly two, refineries. And is transported to the gas station by the same trucks most of the time. So buying from Shell instead of Walmart boils down to only a couple of factors. Additives added to the fuel at the station. And the storage tanks. Additives are mostly snake oil. I remember Chevron getting in hot water for adding Teflon, which does not mix into a liquid, and people having clogged injectors. Storage tanks are impossible for a customer to inspect, but will definitely cause the most problems. Rust, dirt, and water can ruin your fuel system. Best bet is to use the most popular fuel stations. The constant fuel demand, that it's less likely to be full of water and contaminants that tend to build when fuel is stored for long periods of time.

 

[Jeep Dude]

Take this with a huge grain of salt because a may not actually know what I'm talking about but I think this is what he means by hydrodynamic.

Imagine you are riding in a boat and your hand is in the water. At slower speeds your had is being pushed through it however as speed increases, eventually your hand starts to skim across the surface of the water. How does this apply to the timing chain? At slower engine speeds the timing chain is pushing through the engine oil that is lubricating the chain guides so there is physical contact between the chain and the guides. At a certain RPM the chain starts to move fast enough to where is rides across the surface of the lubricating oil and is no longer making direct contact with the guides.

This makes sense to me but could be completely wrong.... ?‍

Thanks for that, nice work, but I will say wow IF true.

I would of loved to have asked him, if this means that idling for any prolonged time on the 3.6, is a no-no?

 

[flyer92]

O.K., you asked about the 3.6 engine. Below is from one of the Engineers that Designed it:

Nice! As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability..... The lighter oil was chosen mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another. A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+. Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings. Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact. Cheers! Kevin PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.

Fantastic insight and thanks for sharing! Only question I have is with respect to the term "WOT."

In my profession, WOT equates to "pedal to the metal" or more specifically, 100% throttle. However, 100% will result in me driving well over 100mph, which I don't care to do on a regular basis, and I can't imagine that the engine's designers intended that either. So....this begs the question: What velocity equates to "WOT" and how long does it need to be maintained to sufficiently lubricate the valve stem seals? 70 mph for 10 minutes? 82.7 mph for 13 minutes 54 seconds? Lots left to interpretation in the excerpt above, so appreciate any specific recommendations or advice. Thanks in advance and happy Jeepin'!

 

[cyked]

Is the 3.6L not port injection, rather than "simply" DI?

 

[Yankee1019]

I would of loved to have asked him, if this means that idling for any prolonged time on the 3.6, is a no-no?

I don’t think extended idling is healthy for any gas engine.

 

[cyked]

I don’t think extended idling is healthy for any gas engine.

This is why at a stop I always rest my foot on the gas pedal to around 3k RPM.

 

[AnnDee4444]

This is why at a stop I always rest my foot on the gas pedal to around 3k RPM.

...this you?

 

[gevo1]

A lot of good info here. I too purchased the 3.6 in 07/2019 as I believe its the most abundant and reliable chrysler engine. Not to say its perfect of course but this meant for an adventure vehicle, I can more readily find parts as needed, at a lower price. I have currently 104k miles. I drive it hard, all the time and had some issues but generally, its been surprisingly reliable.

General things to note:

- The biggest concern for me has always been heat management as I find its always running hotter than I'd like. Running is hard I've at times seen temps in the 250 range. While the coolant temps come down rather quickly, the oil temps take longer.
- Changed to gladiator grill inserts for increased airflow when they became available. This did not have significant improvement but did noticeably affect the time in took for the temps to come back down.
- I've always done 4-5k oil changes with Pennzoil ultra plantinum 5W30. Never was a fan of the 0W20 and felt it was too thin. The engine runs noticeably smoother with 5W30.
- Never used start/stop.
- With the high compression of these engines, I never liked the idea of 89 octane fuel from the start. After running it under high loads, especially at higher altitudes and/or hot days, the engine felt like it was struggling, heating and possibly pulling timing, felt like less power. I initially switched to 91 which helped significantly, including rough idle, as well as reduced a bit of the engine temps as well, especially at high loads, going uphill. Since then, I found 89 to perform the best in my case (including better mpg) without the needed extra expense of 91 octane.
- Replaced transmission fluid/filter, transfer case and differential fluids x2 times each.
- Replaced original battery twice (once under warranty) and after second, I bypassed the secondary battery.

The following performed at the same time around 85k miles:
- Replaced radiator to Cold Case when the original cracked and replaced hose due to leaks (possibly my fault from jumping the jeep a bit).
- Replaced oil cooler/filter housing with Dorman aluminum unit due to original cracking and leaking.
- Replaced spark plugs
- Replaced valve cover seals due to leaks and to inspect the valvetrain (was showing signs of wear but nothing critical)
- Cleaned EGR and tubes (very dirty).
- Intake valves were pretty clean (not running a catch can, although as good one wouldn't be a bad idea). As mentioned, these are not DI engines and a "walnut blast", etc. cleaning service is unnecessary/useless. I did however clean out the intakes, plenum and throttle body as is norm.

Good luck, hope this helps

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