Jeep Grand Cherokee 3.6L proper oil?

[IndyFan]

The 3.6L in my 2019 is the ONLY engine that I ever owned that failed at 50K miles (cracked head or block). There are PLENTY of cam/upper valvetrain issues noted with this engine and while that points to a bad design, you can bet that xW-20 is not helping with that either. Most of these engines run much hotter than what would be considered normal >224F oil temperatures particularly if used off-road.

I would not run anything less than a xW-30 in it just for the extra protection that it affords. The VVT system in a 3.6L is electronic and not viscosity dependent so even a heavy xW-40 (depending on ambient temperatures) will run just fine--there is NOTHING in a 3.6L that requires xW-20 oil. I have a friend in TX who bought his at the same time as I did and he has ran Castrol 0W-40 in it from the first oil change--140K miles later and ZERO issues.

So did the oil cause that, or not? How can a bad design running Lucas oil Stabilizer make it to or past 150K with lots of heavy off-roading in desert conditions? Asking for a friend.

Heck, how can mine make it to 100k on 0w20, towing, revving, and rock crawling along the way? Asking for me.

 

[Bighorn2500]

I can attest to the 3.6L running on anything including pure neglect. My sister-in-law's 2019 Durango has over 223k miles (mainly highway) on it. I have been changing the oil in it since 58,783 miles, as you can see the basic records I keep below note in red where the change came to me beyond the recommend max 10k change interval. I have used whatever on sale/rebated 0w20, 5w20, 5w30, 0w40 I had on the shelf at the time including franken brews. Heck it even got 10w30 CK-4 Diesel oil for top-off when it came over briefly before a trip across state. I just happen to look at the dipstick and there was NO oil on the it. I added almost three quarts to get the full mark. . I have advised them it needs spark plugs, coolant change, serpentine belt & tensioner change till the cows come home and all I get is, yeah I'll look into it . The ONLY other maintenance done EVER was new rotors and pads at 175k.

Not sure what keeps it going, it must be the Honey Badger of engines .

 

[ripcord]

Fact: This is a proven, stout engine with over 14,000,000 built.
Fact: It has one of, if not THE lowest warranty claim costs in the industry for a mass produced engine....of all time.
Fact: It has been on Wards 10 best engine list many times.
Fact: The VAST majority have run on 20 weight bulk (cheap) oil.
Fact: They are known for long term durability. You don't have to look far to find one with over 200,000 miles and they are not hard to find with 300k.
Fact: If .01% have a given issue, most mechanics in the country will have seen it and think it's a huge issue.
Fact: It is not uncommon for mechanics will swear it is some Hocus pocus reason, such as 20 wt oil.

And for you "my valve train will thrash itself to pieces without thick oil" folks.......

Fact: You won't hurt it with 5w30, 10w30, or even a 40 weight oil. So you can calm down and feel better.

My best friend runs 5 quarts of 5w20 in his 2012. He then adds 1 quart of Lucas Oil Stabilizer, which is at the thickness level of cold molasses. The viscosity of that stuff is 110 at 100 degrees C. YIKES!!!!! But somehow, his Pentastar still runs fine. Funny thing...all the guys whose heads tell them that 5w30 quiets the valve train...his Pentastar makes as much clattering noise at idle as any I've ever heard. More than either of mine running 0w20.

Run what makes you feel good. But let's not spread the garbage about 20 weight oils harming these engines. I doubt any of you run yours harder than I run my 2018 JL, and it's crossing the 100k threshold on a 100% diet of 0w20, running just like new. This engine is just a hoot with a manual transmission and sounds wonderful with an axle-back Magnaflow. Especially with the doors off of the Jeep, all summer long.

2018, 6 speed manual...ready to pass 100,000 miles. I have towed a lot with this, too! From 100+degree rock crawling in deserts in the SW to aggressively trying to keep up with my kids' sports cars on twisty roads, it has had a diet of mostly M1 EP 0w20 with a few runs of Shell RGT 0w20 and one of Valvoline EP 0w20. UOA's have been good.

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2021 Gladiator...3.6/8 speed auto...Lots of towing so far, it's off-road career is just beginning. I don't run it as hard as the Wrangler, but as it should, it runs and sounds and feels identical to its twin in the JL. Bulk 0w20 from the dealer for the first 35k miles and its previous owner. 20k with me on Mobil 1 EP 0w20. 55k on it now. I'll probably run this thing for 20 years.
View attachment 256109

2008 JK Wrangler...Sold with 196,000 miles on it. Diet was mostly 5w20 Mobil 1 with experimentation with other oils on occasion, including a few franken-brews. Last 5 or so OCI"s were on 0w20. 3.8 engine/6 speed manual continues to run like new with new owner at about 215,000 miles. He's continuing with Mobil 1 0w20. It always used a bit of oil, as 3.8's do. But never let me down. That's another engine that could run on anything and outlive it's host vehicle.
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I agree with just about everything you say except to argue that 200k is not a particularly long life by today's standards. Today, if an average engine of a particular type can't go over 300k with normal maintenance, it's defective.

 

[CarbonSteel]

So did the oil cause that, or not? How can a bad design running Lucas oil Stabilizer make it to or past 150K with lots of heavy off-roading in desert conditions? Asking for a friend.

Heck, how can mine make it to 100k on 0w20, towing, revving, and rock crawling along the way? Asking for me.

No, it did not. My point is this:

1. 0W-20 is not helping with the well known valve train issues. xW-30 or higher could help reduce the wear.

2. Nothing in the 3.6L is designed to ONLY run xW-20 and given the cost of the same for xW-30 or xW-40, why wouldn't you run it?

I know that you have ran xW-20 and have not had valve train issues, plenty of others who have--count yourself in the "lucky" group.

 

[SunnynHollister]

I run 0W-20 in my 2023 Gladiator because it's under warranty and I got two free oil changes when I bought it. Once it's out of warranty I'll run whatever I have on the shelf when the oil change is due.

 

[IndyFan]

I agree with just about everything you say except to argue that 200k is not a particularly long life by today's standards. Today, if an average engine of a particular type can't go over 300k with normal maintenance, it's defective.

I didn't say they stop at 200k, did I? They can be expected to get there with almost neglectful maintenance. With proper maintenance, sure, they'd go way beyond, typically.

I figured there would be arguments, but this? Lol.

 

[IndyFan]

No, it did not. My point is this:

1. 0W-20 is not helping with the well known valve train issues. xW-30 or higher could help reduce the wear.

2. Nothing in the 3.6L is designed to ONLY run xW-20 and given the cost of the same for xW-30 or xW-40, why wouldn't you run it?

I know that you have ran xW-20 and have not had valve train issues, plenty of others who have--count yourself in the "lucky" group.

So why haven't I had the valve train issues? I don't think that's luck.

The valve train issues are usually a bad part, not a bad design, and not oil related. They are not oil related. A bad part will go bad no matter what oil you use. Most repairs are to replace the specific parts, not the entire valve train. That rules out oil.

But if it worries some, by all means run 5w30. I've seen absolutely NOTHING that implicates oil weight as the culprit for those known issues that affect a very small percentage of these engines. Remember, there are over 14,000,000 that have been made. So to a mechanic in an Indy shop, they'd see those issues all the time and think they are more common than issues for engines with far fewer made that might actually occur at a higher rate.

I'm in 3 Jeep clubs and I've seen not heard of one Pentastar that had an oil related failure and I can think of one 2012 that I heard about which experienced a head failure due to the manufacturing issue they had that year. It was old, I don't know how many miles were on it, but I heard it was covered by extended warranty handed out to those with that model year in Wranglers.

I just don't see the pattern here. Nor do I see a class action suit against Stellantis or an oil company. I'd bet we'd see that if there were evidence of oil failure.

 

[Jetronic]

I was told not to use anything but 0-20 in my 2019 Jeep Grand Cherokee Limited 3.6 V6. The reason was that the cam phasers need that weight oil and if i went to 5-20 or 5-30 the computer would start acting up because of the thicker oil exiting the cam phasers. I know this engine started a bunch of years back with 5-30 and went to 5-20 then 0-20. I'm also told they did this to achieve a fuel mileage rating. I would like to use 5-30 or 5-20. Is this true or was I just told that by a non informed mechanic?

I'm not running a Jeep, but I have a 1.5 ecotec that's specced for 0W-20 and I put it on 10W-30 (thick like a euro oil too) since new. it doesn't care. It's got cam phasers aswell. I'm getting really good mileage to boot.

 

[CarbonSteel]

So why haven't I had the valve train issues? I don't think that's luck.

It sure as heck fire isn't by design...

 

[ripcord]

I didn't say they stop at 200k, did I? They can be expected to get there with almost neglectful maintenance. With proper maintenance, sure, they'd go way beyond, typically.

I figured there would be arguments, but this? Lol.

I wasn't really arguing with you. There's just a lot of people on here that seem to think 200k is a big achievement.