Beware 3.6 Penstar

[badtux]

Factory spec oil weight is too light for such a high rpm reving engine.

Light engine oil is for CAFE standard at the expense of engine wear and consumer's pocket

Actually, a high revving engine needs a lighter oil than a low-revving engine because the oil needs to be thin enough to make it into places that are moving fast. A thicker oil can't get there in time, causing metal-on-metal action. The rocker issues are caused by bad manufacturing tolerances for rockers (i.e. defective rocker arms), not by oil. In particular, using a heavier oil will cause more cam wear with the hydraulic lash adjusters in the Pentastar, because it causes the lash adjusters to "pump up" and put too much pressure on the valve train. The lash adjusters were designed to run with the specified oil, not with a heavier oil.

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[ShadowsPapa]

Uhh, I would be concerned that it is consuming coolant... The coolant system should be closed loop, only limited number of places it can go...

It can evaporate, but it takes a long time to loose much that way.
My first JT went 27,000 miles and 32 months and only needed around 8 ounces of coolant to bring it back to the line I had noted when it was new.

Actually, a high revving engine needs a lighter oil than a low-revving engine because the oil needs to be thin enough to make it into places that are moving fast. A thicker oil can't get there in time, causing metal-on-metal action. The rocker issues are caused by bad manufacturing tolerances for rockers (i.e. defective rocker arms), not by oil. In particular, using a heavier oil will cause more cam wear with the hydraulic lash adjusters in the Pentastar, because it causes the lash adjusters to "pump up" and put too much pressure on the valve train. The lash adjusters were designed to run with the specified oil, not with a heavier oil.

These can easily go up one notch in viscosity.
I'm not leaning that direction, but these could.

Lash adjusters "pumping up" doesn't cause wear - it causes valves to not fully seat. There's the same exact wear as far as the moving parts. You always want as close as possible to 0 lash - more lash makes noise and that's what wears parts. Clearances allows a hammering effect on the parts. Valve trains that are noisy from having clearance wear down faster. Going beyond 0 lash to too tight means valves don't close firmly.
I've seen valve trains with lash - with clearance - hammer themselves to death.

Oil that is too heavy for the clearances and engine needs drives up bearing temperatures, and the oil runs hotter. The sheer action of the heavier oil causes heat. The slower moving oil gets hotter and doesn't pull heat from the engine parts.

 

[Lumis]

42k miles no problems. Never late on oil changes

 

[Akgladiator]

Actually, a high revving engine needs a lighter oil than a low-revving engine because the oil needs to be thin enough to make it into places that are moving fast. A thicker oil can't get there in time, causing metal-on-metal action. The rocker issues are caused by bad manufacturing tolerances for rockers (i.e. defective rocker arms), not by oil. In particular, using a heavier oil will cause more cam wear with the hydraulic lash adjusters in the Pentastar, because it causes the lash adjusters to "pump up" and put too much pressure on the valve train. The lash adjusters were designed to run with the specified oil, not with a heavier oil.

Wrong. BMW high revving v8 uses thick oil. Your engine your choice...

Don't come to forum and complain your engine ticking or dead...

 

[ShadowsPapa]

Your engine your choice...

Define "thick oil".

IF it's too heavy, you'll have heating issues, and possible malfunction of the VVL - among other possible issues.

Each engine is engineered with different clearances and parts designed to work withing certain parameters.
So if you go far enough away from the recommendations, don't whine here if it blows or there are issues.
The recommendations are for keeping the engine going. Yes, they consider CAFE and EPA - but they don't give a rip about CAFE numbers after it's bought and on the road. The numbers in the book are to keep you from coming back on them with issues under warranty.

People get all caught up in the oil thing and assume they know better, or can base it off what some other engine is engineered for.

These aren't BMW engines.

 

[dos0711]

5W-30 here in the sunshine state.

 

[NormanF]

the 3.6 pentastar has been around for 10 years and used on many other vehicles. I do feel that it is probably not the best engine for the Jeep but hasn't been bad. I believe they should retard the timing a bit due to engine pinging when under stress (at lower RPM such as when changing to next gear up). This can be offset with premium fuel (or perhaps retarding the timing) or adding (as I do) an octane booster and avoiding the "ping". Excessive pinging will damage the engine and perhaps that is what the OP was reporting..

 

[FLRTHD1]

Have 121,000 on my 12 unlimited with 3.6, recall on left head with in the first year. Head replaced and given a 150,000 warranty. NO ISSUES, NO OIL USES !

 

[ntwrkguru]

Factory spec oil weight is too light for such a high rpm reving engine.

Light engine oil is for CAFE standard at the expense of engine wear and consumer's pocket

? And I *just* took off my tinfoil hat.

 

[ShadowsPapa]

the 3.6 pentastar has been around for 10 years and used on many other vehicles. I do feel that it is probably not the best engine for the Jeep but hasn't been bad. I believe they should retard the timing a bit due to engine pinging when under stress (at lower RPM such as when changing to next gear up). This can be offset with premium fuel (or perhaps retarding the timing) or adding (as I do) an octane booster and avoiding the "ping". Excessive pinging will damage the engine and perhaps that is what the OP was reporting..

Pentastar was first used in Jeeps. (Grand Cherokee in 2011, Wrangler in 2012_) so IMO, it's actually a Jeep engine.
Keep it out of the lower RPM, shift later.
True pinging isn't common on these - especially with automatics so............ is it that people are shifting too quickly and not winding them up?
I've watched the timing on these - I see some really low, even ATDC, numbers, now and then.
I only see the big advance numbers when not under stress or lugging.
I run 87 most of the time, U88 when I can get it, never heard a rattle out it.

IMO, from what I've been reading, people with the manual transmissions need to wind these up and not shift so soon.

Some ping won't hurt anything on these - so far we've not seen any damage from true detonation.
Using crap oil can lead to the ping of LSPI, so that's another thing to look for. That's one of the things the new oil specs is for. LSPI is very problematic, more that detonation ping.

 

[Koolcarguy]

I’m sure the diesel is more unreliable overall

Crazy you say that we have 4 Diesels 3 21's and a 22 3 Jt's and 1 Jl total of 85++ miles on the 4 and not 1 issue. Also had 65k miles on a 20 Jt 3.6 with 37's and not 1 issues? My 12 Jk on the other hand got a brand new motor at 35k miles

 

[In3briatedPanda]

Thats where I was trying to get at - so long as they make it right - thats what matters. I've had cars that were supposed to be bulletproof reliable - but ended up having cracked heads, head gasket issues etc (mainly alot of 3VZE powered Pickups/4runners in the past).

ive never see that on the 3VZFE, over heated 1MZFE is another story. Maybe i missed those old V6's Id love to find a 7M out of a cressida.

 

[Kenny Erhardt]

I’ve owned numerous Jeeps - including 392 and diesel. My latest purchase was a brand new 2021 Mojave and I foolishly opted for the 3.6 motor due to it’s length of production, assuming all the bugs were worked out long ago. At 3,000 miles after the first oil change, the oft-reported “ticking” noise began due to faulty lifters. At 10,000 miles it sounded like a diesel! I took it back to the local Jeep dealer. Had to make an appointment and bring it back 10 days later. Now 2 weeks later, they still have not had the time to look at it, much less work on it, nor to order parts. Granted, they did give me a loaner, but after spending $80,000 (with considerable modifications), my jeep is greatly depreciated (carfax will reflect engine work), can’t be driven, and who knows when I will get it back? The lesson to all this is: read about the class action lawsuit against Jeep for defective 3.6 engines with lifter design flaws before making my mistake!

I Have a 2021 Rubicon 20,000 miles no Problems

 

[Gladiator Brad 704]

30K and running strong. 21 MPG as reported by the computer in the dash.

 

[Tommyd]

meh, 150K on my 3.6 minivan engine, tons of time sitting and ideling in carpool/parking lots too and still running like a top. It's not my favorite engine by far, but it's not my biggest worry on my gladiator

whats your biggest worry?

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