3.6 Pentastar viscosity done by clearance and temperature

[Camperguy]

Honestly I went strictly by bearing clearances and operating temperature. I'm just stating what I did and why. If you're still under warranty I would do whatever they want you to do but probably more often to be on the safe side. My Jeep is 10yrs old and way past Warranty and even if it wasn't they wouldn't cover it because of all the mods I've done.

 

[kschachn]

Also be aware that chart has a lot of nonsense in it, at least as far as it goes with the grades. It’s more of a sales tool.

 

[Camperguy]

Sales tools for what ?

 

[kschachn]

Sales tools for what ?

Driven. They like to designate their own grades as you see in the chart. I do not like them for that reason.

 

[Camperguy]

So bearing clearances pertain only to their oil?

 

[kschachn]

So bearing clearances pertain only to their oil?

That chart does. And some of those grade designations are only the imagination of that blender so they can make them out to whatever they want them to be.

Plus you don’t need thinner oils like that for those tighter clearances. It only means you can but it’s not required.

 

[Camperguy]

https://www.enginelabs.com/ They're an engine builder site

 

[kschachn]

https://www.enginelabs.com/ They're an engine builder site

Okay.

 

[Camperguy]

And

 

[kschachn]

And

I have no idea what you’re trying to say. That site has some nonsense on it as well. That “flow test” down the plastic ramps is not representative of what happens inside of an engine. It’s only representative of what happens when you try to flow oil down little plastic ramps.

Plus I see they are promoting a brand of oil as well.

 

[Camperguy]

1/8 & 1/4 mile is what the thin stuff is for. Guys looking to eek out a few more HP on a full power run. Though I've never seen repeatable results on a Dyno, considering fuel dilution and blow by I never would chance it unless I was sponsored.

 

[Camperguy]

Lake Speed JR was the original article where I actually found the clearance chart. It makes perfect sense having used Plastigauge a couple of times.

 

[kschachn]

1/8 & 1/4 mile is what the thin stuff is for. Guys looking to eke out a few more HP on a full power run. Though I've never seen repeatable results on a Dyno, considering fuel dilution and blow by I never would chance it unless I was sponsored.

Yes racing has different expectations, assumptions and objectives for sure.

 

[INTENSE]

I currently run 5w-40 Mobil 1 Euro spec API SP. So far so good. Much quieter. No noticeable loss in economy in my 21 Rubicon.

If I understand correctly, the 2012 Pentastar had 5w-30 recommended. Can someone point to a resource for main, and cam journal clearances, etc? I’d like to use that information along with cumulative knowledge of what viscosity works with those clearances/temps and put it all to bed.

 

[INTENSE]

I currently run 5w-40 Mobil 1 Euro spec API SP. So far so good. Much quieter. No noticeable loss in economy in my 21 Rubicon.

If I understand correctly, the 2012 Pentastar had 5w-30 recommended. Can someone point to a resource for main, and cam journal clearances, etc? I’d like to use that information along with cumulative knowledge of what viscosity works with those clearances/temps and put it all to bed.

I went to Speedtalk and got a machinist to answer from their resources where I couldn’t find what one was really available online, oil clearance specs. The rod and main clearances are the same between a 2012 3.6 Pentastar and my 21 3.6 Pentastar in my Wrangler. In regards to cold oil flow characteristics between when they initially recommended a 5w in 2012 or thereabouts to now recommending a 0w, there should be no detriment going up to 5w.

 

[hawkdriver]

Owned a 2014 Rubicon for a short time. Here's what the manual said: "Engine Oil Selection — ACEA Categories For countries that use the ACEA European Oil Categories for Service Fill Oils, we recommend you use engine oils that meet the requirements of ACEA C3 and approved to Chrysler MS-6395 or Fiat 9.55535–CR1. Engine Oil Viscosity (SAE GRADE)MOPAR® 5W-20 engine oil is recommended for all operating temperatures. This engine oil improves low temperature starting and vehicle fuel economy......MOPAR® SAE 5W-30 engine oil approved to Chrysler Material Standard MS-6395 or Fiat9.55535-CR1 may be used when SAE 5W-20 engine oil is not available."

 

[rikster]

Interesting, I'm getting ready to do another oil change on my JLU with the 3.6. I thought the revised 3.6 like I have was designed for 0w20 with thinner passageways and that was the best for it. Wrong?

I found this and it seems to answer that:

"The same, tired oil thread. Yet again.

A 626,000-mile 3.6L Pentastar ran on 20 weight oil: https://www.macsmotorcitygarage.com/video-inside-a-chrysler-pentastar-v6-with-626000-miles/

And straight from the horse's (engineer's) mouth, for the millionth time: 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.

Run. What. The. Manual. Says. It's generally a good idea to rely on the oil the engineers used when they spent tens of millions of dollars designing and stress-testing that engine before final production.

Assuming that running the OEM recommended oil is what caused one of the millions of Pentastars on the road to develop a tick/knock/chatter is, frankly, idiotic.

No ****, Sherlock: A thicker oil will quiet down a mechanical issue that was probably caused by something beside merely running the recommended oil."

 

[Lockasiam]

why does e85 make a difference

 

[Slick3914]

why does e85 make a difference

Oil dilution

 

[INTENSE]

I found this and it seems to answer that:

"The same, tired oil thread. Yet again.

A 626,000-mile 3.6L Pentastar ran on 20 weight oil: https://www.macsmotorcitygarage.com/video-inside-a-chrysler-pentastar-v6-with-626000-miles/

And straight from the horse's (engineer's) mouth, for the millionth time: 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.

Run. What. The. Manual. Says. It's generally a good idea to rely on the oil the engineers used when they spent tens of millions of dollars designing and stress-testing that engine before final production.

Assuming that running the OEM recommended oil is what caused one of the millions of Pentastars on the road to develop a tick/knock/chatter is, frankly, idiotic.

No ****, Sherlock: A thicker oil will quiet down a mechanical issue that was probably caused by something beside merely running the recommended oil."

Not necessarily if you pay the price to get an oil that flows better at ambient and also provides more protection at operating temp.IE, sub -40° pour point for the valvetrain but higher viscosity at operating temp to reduce wear elsewhere vs the API Spec 0w-20. Oils like some pricier 5w-30, 0w-30, 0w-40 with pour points of -58 to -60 like HPL offers mixed in their lineup like their Premium and Premium Plus lines or their No VII line.

And there’s 3.6 lifter/cam failures with perfect maintenance, very good oils/filters, regular changes and, at this moment, almost 12k backordered passenger intake cam kits. 500 just shipped. There’s regularly 1 or 2 3.6’s or 3.2’s in dealership service bays every week. At minimum, they need to revise the oil change interval recommendation because the 0w-20 is right on the edge of “good enough”. This guy you quoted obviously concedes the fragility of the engine and two opposing needs it has. That’s not necessarily the greatest design in my automotive machinist opinion.

Then you throw in varying operating conditions and maybe some somewhat neglectful owner factors (maybe they went over a couple thousand miles once) and it shows there’s not much reliability margin built into this engine. Then…there’s head bolts not being torqued properly and/or cylinder movement (no webbing supporting the top/open deck), defective bolts possibly as well and you have more, likely, possible outlier factors.

I wouldn’t call it a bad engine, but this guy acknowledges a viscosity conflict. That’s not the consumers fault. Consumers aren’t necessarily the professional like this guy is supposed to be. Instead of fixing it, this guy is essentially saying “haha that sucked” we found this and left it that way rather than spending money to start with a clean sheet on the valvetrain and oil supply system.