Kojack

No conspiracy theory there. Its a fact. Why, back in the early model years of this engine was 5w30 the recommended oil? Then, when all auto manufacturers were sqeezed by the nuts to make better milage from their entire lineup, did it magaically switch to 5w20? Think about that. Thinner oil, more gas milage possible. Same motor, same tolerances, thinner oil? I think they should recommend 5w40 from the factory for the 3.3 and 3.8 motors.

My jeep is due now for a change. I am going to just use the motomaster dino 5w40 and try that out to see how the motor reacts. I am going to use their oil filter etc.

I will report back on the results. I will keep a close eye on the oil burn etc. If it works, then I will switch to amsoil the next change.

Ryan0260

The 3.8 definitely does better with the thicker oils, and yes the specs were changed to improve fuel economy, while the tolerances stayed the same. I wouldn't run less than 5W30 in that motor, and I imagine the 5W40 will be fine as well, especially if you are burning oil.

Kojack

We will see what my results are. I will keep track of my gas milage after the 5w40 goes in.

Mr.T

It's been a bit over 9K miles without needing to add any oil, maybe it's due for an oil change???

This oil change interval has had a lot more short trips to town, about the same percentage of 4LO time, but a lot more full throttle near redline climbing mountain passes in third gear. Fuel is cheaper, and this engine at full power just sounds happy to me. The longer I own this Jeep, the more I like the 3.8L engine. It's got sufficient power, but to get full power it needs RPM near 5K -- So how might this more severe usage affect engine wear?

Here's what oil analysis had to say...

Aluminum (AL) 2 ppm
Iron (FE) 16 ppm
Copper (CU) 18 ppm
Lead (PB) 0 ppm
Tin (SN) 0 ppm
Chromium (CR) 1 ppm
Nickel 0 ppm
Cadmium 0 ppm
Silver 0 ppm
Vanadium 0 ppm
Silicon 13 ppm
Sodium 12 ppm
TBN 4.1

The answer: Wear metals are still very low, especially after 9000 miles of collecting wear particles. It looks pretty much the same as prior oil analyses.

Notes:
Amsoil DEO 5w-40 (diesel/gasoline rated) oil. Using an oversize oil filter that is used on the 2008 Jeep Liberty 3.7L, and many other engines (NAPA PFL 41516, Wix 51516XP). Total miles using 5w-40 are about 56K. Total miles on Jeep are a bit over 66K.

DECKER

One thing to keep in mind is there is always going to be some sort of wear material in the oil. With that said you need to establish a base line for what is normal wear with your engine. If you do notice an abnormaliti aka an increase then that would be cause for concern. With running a thicker oil you must understand why the Jeep recommend the oil it did. Things like oil jurnals, and tolerances play a major role. If you up the thickness, you could risk prematurely wearing parts. This will be a snow ball effect down the road. Worn parts will eventually lead to burning more oil. Note when switching to a thicker oil you will notice less oil consumption but that is most likely due to oil not getting to places it should. Sorry for rambling on.

Mr.T

There's over 50K miles and multiple samples I've posted here, and the trend is clear. Low wear metals are ALWAYS a good sign, and the wear metals are low compared to others I've seen posted on jk-forum and elsewhere, especially given the long oil change intervals (the last was 9K miles). This is real data -- Speculation about increased wear with 5w-40 is just that, speculation.

Given this data, I don't understand how you came to the conclusion that with 5w-40 "If you up the thickness, you could risk prematurely wearing parts."

Your "oil isn't getting to the places it should" and "snowball effect" hypothesis would have to show a trend increase in wear metals -- If it hasn't materialized in 56K miles, it's either not a valid hypothesis or the body will be entirely rusted out before this snowball even gets rolling.

Regarding the oft mentioned "base line", while there certainly is value in trending, there is also much value in comparison with normal values and averages.

For example, someone begins oil analysis and the readings are significantly above average for wear metal(s), and after years with a steady trend of higher than normal wear (and a bunch of excuses why this engine has always had high wear metals in the oil), the engine wears out or fails per-maturely. In this example, the absolute value (from even the first sample) was telling the user something was abnormal (albeit chronic rather than acute).

Side note Blackstone has an express oil analysis kit for those buying a used car if anyone might be thinking about getting engine oil tested before finalizing a purchase.

jeepmojo

Harley davidson used to say do not run synthetics in their motorcycles it will destroy the motors . People found that not to be true . Now harley davidson is selling harley davidson synthetic oil for all harleys suggesting not to use any other oil .
however im a dino believer just change oil & filter every 3000 miles.


i have a 3.6 wonder if oil thicker than 5 -30 is better for those too .?
i use the 5-30 as recommended . But it makes you wonder if they really know more than
the owners seeing results like i just read .

im not a motor head so i generally listen to the manufacture for the most part. though 10/30 oil was always the old standard for most cars years back but things change i guess(technology)

grim_creation

I'm thinking it's time to switch to a higher viscocity oil here and after reading this thread and experiencing my problems below, it's time.

My Jeep has always been a little weird with the oil change light, would go off at 3k like clockwork and I'd check the oil, determine it's fine, then reset the oil change indicator with the gas pedal reset.

However, this past time is different. I got the oil change indicator at 3k like every other time, but I've been pulling 70 hours a week at work this past month(because I can and like the paycheck) and didn't check it. So I thought I heard something the other day stopped at a stoplight, and thought "I haven't checked that in a while", and got to work, let it sit, then at the end of the day when I went to leave, lo and behold it was low. I don't mean like just under the safe line, oh no, this thing had 1 quart left in it. 1! Couldn't believe it.

So i started thinking about what it could be, and realized that I switched filter brands because it's all they had at wally world at the time. Bosch. Every other time it's been Wix, Fram, or K&N with valvoline 5w-20 full synthetic. This time I switched it up and am regretting it because the engine now makes a weird shucking sound/dry sound when idling, only sometimes though. Luckily for me I was going to change the SO's oil and had a full five quarts sitting in the back to throw in.

So now I'm thinking of changing the oil completely to get that filter off of there and start fresh and after seeing this thread I'll be switching to a thicker oil. Probably not as drastic as a 40 weight oil, but definitely a 30.

Now one thing I need help with is locating a thread from a while ago. It was about oil filter options where someone had used an extremely long filter on their JK. It got me thinking that more filtration would be better and help the oil last much longer especially with the thicker viscocity.

Anyone have any ideas on what filter would be better, or what that thread might be with the filter options?

Just wanted to share that engines can change and adding something different can drastically change the performance of an engine.


Also, on a side note. When I poured the extra oil in I couldn't believe how thing the oil was. Might as well be putting olive oil in the damn thing. It's almost water!

Mr.T

grim_creation: Regarding 3.8L engine oil filters, this is from the last part of my post #54 above:

This is from my post #12 in this thread, thought it might be relevant (or just worth reading).

grim_creation

I'd seen the note about the oversize amsoil filter. And I'll probably go with the wix version of that, or size, which I found. The part number is 1516/1516XP.

There was a thread a long time ago I remember reading(back when tapatalk was still supported) that had a filter that was probably 2.5x the size of the standard filter with the same numbers that someone had posted about. That's what I was trying to find, although it could be this filter. I'll know when I pick one up tonight to change the oil.

My thing is, switching to higher voscosity oil after running specific oils for an extended period may damage your engine(or that's what I was taught). That may not be relevant anymore with newer engines, but why risk damaging something by just jumping to a much higher viscosity oil. Least a person can do is step up into it and let the engine get used to it. Kinda like weening a dog off of puppy food, slow and steady.