Maximize 3.6 Reliability

[Jeep Dude]

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

Sure, with this logic, extended WOT is not healthy for any gas engine either ?.

Curious what HE would of said, was my real point in my post. ?

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'!

Not so much about velocity, but load and rpm.

It boils down to the Italian tune up, it's all about common sense, right? ?

You don't want WOT from a dead stop. This stresses out other components, that need not be stressed out during an Italian tuneup.

Attempting WOT is usually more desirable at higher gears. It allows you to listen out for ?? pinging/detonation, and gives one time to back off the pedal if it occurs(very helpful during high hp tuning). It also causes less wear on other components in higher gears, like tires, diffs, etc...

So if you don't live near the Autobahn, your best bet is 3rd gear WOT to your speed limit, back off, wash rinse repeat every so often

How often?

You tell me ?

@flyer92 I wasn't directing this directly at you, lol

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[UncleJimmy]

So which oil is better, thicker or thinner. He (the engineer) contradicted himself. Or change viscosity for seasons?

 

[Old Dogger]

No, he did not contradict himself. He explained it very well, that in certain areas like the timing chains, thicker has a positive impact. In other areas like the valve train the thinner oil wins out.

 

[UncleJimmy]

So I should just split the difference then?

 

[flyer92]

You don't want WOT from a dead stop. This stresses out other components, that need not be stressed out during an Italian tuneup.

Attempting WOT is usually more desirable at higher gears. It allows you to listen out for ?? pinging/detonation, and gives one time to back off the pedal if it occurs(very helpful during high hp tuning). It also causes less wear on other components in higher gears, like tires, diffs, etc...

So if you don't live near the Autobahn, your best bet is 3rd gear WOT to your speed limit, back off, wash rinse repeat every so often

How often?

You tell me ?

@flyer92 I wasn't directing this directly at you, lol

All good...and this is exactly how I've been doing Italian tune-ups since I started driving carburated CJs decades ago. I just figured that if the advice was coming from an engineer, he might have provided something a little more specific....you know...like an engineer! Otherwise, I agree...it's pretty much common sense.

 

[JJMalone]

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.

When it goes hydrodynamic means when there is no metal to metal contact, ie There is an oil cushion between the rollers and pins and between the rollers and sprocket. Because of the small points of contact, going hydrodynamic takes a lot more speed. The main and rod bearing journals are big enough that they go hydrodynamic immediately when the engine is started.

 

[speedymart]

Honestly the 3.6l is relatively reliable, and most issues are easy to fix.

That being said change your oil every 5k with OEM filters, and if you tend to rev it over 4k a lot I'd suggest using 0w-30 over the 0w-20 it normally runs. 0W-20 turns to literal water at higher temperatures, so if you red line it a lot I'd go with the thicker oil. FWIW this engine was originally designed for 5w-30 oil back in 2011, and has been changed around a bit since then. If you're running an older 3.6 that takes 5w-20 I'd also suggest running 5w-30

 

[cyked]

So I should just split the difference then?

50/50 mix, obviously

 

[bthomp]

Such a good thread! I wish I understood it all though!?!?! This one is worth re-reading and doing some side research on.

 

[OldGuyNewJeep]

Such a good thread! I wish I understood it all though!?!?! This one is worth re-reading and doing some side research on.

LOL, really? I just see a few common sense replies mixed in with a bunch of “a fool and his money are soon parted” recommendations.

Change the oil every 5,000 miles. Don’t buy crappy gas. Enjoy your Jeep.

 

[c20040215]

I have the same engine for the same reason with the same goal. Almost every time I pull the Jeep in the garage, especially in warmer weather, I open the hood. My reasoning is the faster all the built up heat dissipates, the longer all the rubber, plastic and electronic components will last.

Unfortunately, that would not help.
What kills the rubber, seals, plastic and gaskets is the heat up and cool down cycle.
The more heat cycle those components go thru, the quicker they disintegrate.

 

[bthomp]

LOL, really? I just see a few common sense replies mixed in with a bunch of “a fool and his money are soon parted” recommendations.

Change the oil every 5,000 miles. Don’t buy crappy gas. Enjoy your Jeep.

LOL! Okay, yes that is a fair statement. But as an engineer by trade (IT, not mechanical), I am fascinated by the details. Differences in oil viscosity, octane, rod bearings and rollers and pins, stuff I just don't know nearly enough about. Now if I can just drop hydrodynamic into casual conversation,,,, lol. ?

 

[speedymart]

So which oil is better, thicker or thinner. He (the engineer) contradicted himself. Or change viscosity for seasons?

Run 0w-30 or 5w-30 depending on your engine year. I ran 5w-40 on my supercharged JK for 30k miles without any rocker issues.

 

[1BadManVan]

Honestly the 3.6l is relatively reliable, and most issues are easy to fix.

That being said change your oil every 5k with OEM filters, and if you tend to rev it over 4k a lot I'd suggest using 0w-30 over the 0w-20 it normally runs. 0W-20 turns to literal water at higher temperatures, so if you red line it a lot I'd go with the thicker oil. FWIW this engine was originally designed for 5w-30 oil back in 2011, and has been changed around a bit since then. If you're running an older 3.6 that takes 5w-20 I'd also suggest running 5w-30

The engine in the JL is very different than the previous Gen. many many internal changes and was actually designed around 0w20. One of the few engines where the recommended viscosity doesn’t vary by country/region. It’s 0w20 world wide for the pug motor

 

[CarbonSteel]

Walnut blasting the backside of the valves is not needed--the 3.6L is an MPI engine, not DI. Use a good fuel injector cleaner frequently.

Run 5W-30 or 0W-30 oil and change every 5K miles.

Run an oil filter which can filter down to 20 microns @ 99% efficiency. Take EXTREME care not to overtighten the oil filter cap.

Run a top quality air filter--not a K&N type.

If you run a catch can, make sure it's NOT a UPR which has a crappy hose design and will crack and leak on your passenger oxygen sensor and ruin it.

Change your axles and transfer case fluid early and often. Use 75W-140 in the axles despite what FCA says. If a Rubicon, pot the locking sensors with epoxy at 5K miles when you change fluid for the first time.

Change your automatic transmission fluid and filter at 50K miles and perform 3 or 4 dump and fills within the next 10K miles to replace nearly all of the old fluid.

Be prepared to change your auxiliary battery in about 3 years or less. Change both batteries when you do.

Drive your Jeep frequently and enjoy!

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