Mobil 1 FS 10W-30 Jeep 4.0L 3000mi OCI

[MechEng13]

I am a new member, but I have been using the information on BITOG for a few years. Recently, I bought a '95 Jeep XJ with about 95,000 miles. Since owning it, I replaced the timing chain, rear main seal, & water pump. Considering the new internal parts/seals, the Fe & Si ppm are not going to be accurate or useful. This UOA was more of a way to verify the additive package in the Mobil 1 & give me peace of mind that I have a good motor.

Here are the specifics:

Oil: Mobil 1 Full Synthetic 10W-30 (not the HM, EP, or other. Just standard FS).
Oil Filter: Mopar 090
Air Filter: AEM Dryflow
Fuel: Ethanol-free 89
Other: Magnet used on the outside of the oil filter
OCI: aprx. 3,000 Miles

I have heard/read many "bad" things about running Mobil 1 FS in a Jeep 4.0L, but I have always had great results in my other daily drivers and decided to use it anyways. After dropping the Mobil 1, I switched to Valvoline VR1 10W-30 Full Synthetic. I plan to run that oil for 3-4K miles and send in a sample to ALS labs next year. Contrary to internet myth, the greater ZDDP level in VR1 FS is not necessary for the 4.0L and most likely will not improve wear characteristics. BUT the oil is a neat blue shade & there's a cool American flag on the bottle, so I figured my Jeep needed it.

All joking aside, I like the additive package of the new Valvoline VR1 FS and the HTHS values (7.8cP & 3.25 cP @ 100C & 150C respectively). It is the only oil I could find that has slightly more zinc but still retains a decent amount of detergents. I will report back with the new UOA results next year.

 

[SubieRubyRoo]

Silicon is the only really concerning thing, and may be leading to higher iron numbers. 9ppm/1k miles seems high but I don’t peruse many Jeep UOAs. Check your air filter seal & fit, along with the intake piping. Make sure everything is sealed and snug. Monitor & report.

WELCOME!

 

[Greasymechtech]

Consider a 0w40 or 5w40

 

[Zaedock]

Consider a 0w40 or 5w40

I recently changed my trail YJ (2.5L/SM420 transmission/Atlas T-case) to Castrol 0W40. Runs nice.

 

[LouC]

Make sure that the air filter is properly installed & the clips on the housing are all properly clipped in place. I had this same issue on my 07 Jeep 5.7, one of the clips was missing; when I changed it to a Mopar cold air intake the silicon actually went down.
BTW I also have one of those Jeep 4.0 just did my first UOA @ 181,000 miles and it came out surprisingly well. I’ve been using Valvoline Max Life 10/30 or 5/30.

 

[KCJeep]

That's lower than average iron numbers for Mobil 1 in a Jeep 4.0, but still a bit higher than what you would probably get with Rotella, Maxlife etc. Viscosity is a bit lower than I'm comfortable with for a Jeep 4.0 as well.

As mentioned above already, a 5w40 is about perfect for a 4.0 and can be found in "Euro" options with a high level of additives friendly to the venerable 4.0.

 

[Zaedock]

I recommend searching through old threads from a member named Gary Allan, who passed away in April of 2011. He ran some custom ultra-low viscosity brews in his Jeep TJ. Interesting reading from a super cool guy (RIP).

 

[SC Maintenance]

Consider a 0w40 or 5w40

Aren't most of those oils low SAPS - which might be counterproductive with an engine of that vintage?

 

[Greasymechtech]

No, most aren't low SAPs

 

[MechEng13]

Thanks guys! I appreciate the replies.
I am not concerned about the silicon level, considering the oil pan gasket, thermostat housing gasket, timing cover gasket, and water pump gasket were all replaced while this oil was in use. I always use a light coat of Permatex on the mating surface for a perfect seal.

From what I have read, the Iron number is average for a Jeep 4.0L. These Jeeps seem to shed more Iron than most! Over all, I am happy with Mobil 1, and would not be afraid to use it in a 4.0L again. That said, like you all have mentioned, there are better suited oils for a tractor engine like the I6 4.0L. For whatever reason, cheap Pennzoil yellow bottle seems to be the flavor of choice for Jeep owners. I might run that oil once it is time to drop the VR1. I have also heard great things about Amsoil Signature Series, but can't bring myself to pay the price.

 

[addyguy]

Pennzoil YB 10W-30 is a great fit these engines it seems.

 

[MechEng13]

One year later...
Last year, instead of VR1, I decided to go with Amsoil Signature Series 10W-30 (date code 2022). The UOA is attached below.
Based on the results, I see no reason to pay $15 per qrt for this oil.

This year, I will be using Valvoline 5W-40 Premium blue. I will post a new UOA next January.

Oil: Amsoil Signature Series 10W-30 (2022).
Oil Filter: Mopar 090
Air Filter: AC Delco filter in stock air box
Fuel: Ethanol-free 89
OCI: aprx. 3,000 Miles
Date in use: Jan 2023-Nov 2023

 

[Brons2]

Wow vis 9.2 on Amsoil SS10w30? What is the starting viscosity?
I don't recall the Jeep 4.0 being prone to shearing oils down, it's a pretty simple engine.

If you wanted to try another boutique synthetic another year, I would try HPL No VII oil, it will probably gain rather than lose viscosity. You'd have to run it for 2 years to make it make sense, but, HPL offers some oils with very high TBN.

 

[kschachn]

Wow vis 9.2 on Amsoil SS10w30? What is the starting viscosity?
I don't recall the Jeep 4.0 being prone to shearing oils down, it's a pretty simple engine.

If you wanted to try another boutique synthetic another year, I would try HPL No VII oil, it will probably gain rather than lose viscosity. You'd have to run it for 2 years to make it make sense, but, HPL offers some oils with very high TBN.

More likely fuel dilution. I don’t see that on the report. And yes knowing that start is key.

 

[MechEng13]

Thanks for the suggestions! Unfortunately I do not know the starting viscosity.
The diagnosis of the report is show below. Fuel dilution was normal.

 

[M1Accord]

I thought timing chain lasts either lifetime or more than 200k miles in heavier applications.

M1 FS for 3k OCI is a waste of oil let alone Amaoil. If there is no leak so far with FS, go with Kirkland and 5k OCI. If you must use the best synthetic oil, go with Penzoil Ulta, which is 99% as good at half the cost. Amsoil is meant for people going over 15k OCI for the cost factor and they don’t have the economy of scale to sell at lower prices in addition to so many middle men between the makers and the users.

The 4.0 I6 is 300k rated engine with minimal maintenance. The AT is Japanese made too.

 

[MechEng13]

I thought timing chain lasts either lifetime or more than 200k miles in heavier applications.

M1 FS for 3k OCI is a waste of oil let alone Amaoil. If there is no leak so far with FS, go with Kirkland and 5k OCI. If you must use the best synthetic oil, go with Penzoil Ulta, which is 99% as good at half the cost. Amsoil is meant for people going over 15k OCI for the cost factor and they don’t have the economy of scale to sell at lower prices in addition to so many middle men between the makers and the users.

The 4.0 I6 is 300k rated engine with minimal maintenance. The AT is Japanese made too.

Usually 150k-200, but this timing chain had deflection just over factory spec at 95k.

My Jeeps are not daily drivers and usually only accrue 3k miles in a year's time. Sure, the oil would last longer, but I am happy to spend $30-50 a year on one oil change. These UAOs are purely out of curiosity rather than necessity.

 

[kschachn]

Thanks for the suggestions! Unfortunately I do not know the starting viscosity.
The diagnosis of the report is show below. Fuel dilution was normal.

View attachment 200371

One would need to know the method of determination to understand if they can measure it properly or not.

 

[MechEng13]

Although I don't have the starting viscosity of my sample, it should be close to Amsoil's stated value- 10.0 centistokes at 100*C. Fairly low for a 10W-30 oil to begin with.

ALS Labs states that they use calculated viscosity/flash point to determine fuel dilution. Given that this engine is fuel injected and just about everything in the fuel system is new, I have my doubts that the shear is due to fuel dilution. Does anyone know the average shear after a standard OCI? 0.8 centistokes does not seem significant, but I am open to learn from the BITOG experts.

 

[kschachn]

Although I don't have the starting viscosity of my sample, it should be close to Amsoil's stated value- 10.0 centistokes at 100*C. Fairly low for a 10W-30 oil to begin with.

ALS Labs states that they use calculated viscosity/flash point to determine fuel dilution. Given that this engine is fuel injected and just about everything in the fuel system is new, I have my doubts that the shear is due to fuel dilution. Does anyone know the average shear after a standard OCI? 0.8 centistokes does not seem significant, but I am open to learn from the BITOG experts.

View attachment 201271View attachment 201270

I would doubt that result as being accurate.