UOA Valvoline VR1 15W-40 Jeep 4.0L

[MechEng13]

Jeep 4.0L with 214,000 miles
3,000mi OCI
3qrts VR1 10W30 + 3qrts VR1 20W50
Mopar M090 Filter
ALS Tribology

I bought this Jeep last September. It has pretty severe piston slap on cold start, to the point that it sounds like a diesel engine until it warms up. After bore scoping each cylinder and checking the bottom end when replacing the rear-main seal, it appears to be completely original (original pistons and cam at least). I planned on rebuilding the motor over the winter, but this analysis might have changed my mind. The piston slap bugs me, but the engine does not burn a drop of oil and runs like a Swiss watch once warm.

As a comparison, I have another 4.0L motor with 135k miles that was rebuilt at some point in its life. That motor showed around 30ppm of Iron and about 5ppm of aluminum. From what I have read, 30-50ppm Iron is pretty standard for the 4.0L.

Photo of the worst cylinder wall. Consistent wear for 214k miles!

 

[fantastic]

5 PPM/1k Fe is at the higher end of "acceptable" IMO. Not bad though & the bores do look really good for the mileage. The knock could be connecting rod wear though which would require a tear down to inspect (unless can access via oil pan). Si is very high so please go inspect your intake filter & plumbing. Viscosity of this "15w-40" mix is no longer a 40 grade but more than adequate for this engine.

This is an older VOA but it only shows 7 ppm Si.
https://bobistheoilguy.com/forums/threads/voa-valvoline-vr1-20w50.254289/

 

[burbguy82]

Silicon would suggest air filtering is an issue.

It looks like you have a stuck ring.

 

[Gene K]

It looks like you have a stuck ring.

A stuck ring without oil consumption?

 

[burbguy82]

sure

A stuck ring without oil consumption

How else does one part of the cylinder wear like that?

 

[burbguy82]

sure


How else does one part of the cylinder wear like that?

I would ditch the VR1 mix for now, and run a higher detergent oil than SP. It might help.

Evidently, VR1 is of an "SP compliant" (for lack of the ability to explain it better) formulation, with lower detergents, which evidently adds to the anti wear characteristics, but not good for the "cleaning of existing" conditions. I am not an oil expert, but this is my base line understanding.

I would try

https://www.amsoil.com/p/amsoil-sig...thetic-max-duty-diesel-oil-deo/?code=DEO1G-EA

or

https://www.amsoil.com/p/amsoil-premium-protection-10w-40-100-synthetic-motor-oil-amo/?code=AMO1G-EA

or

https://www.amsoil.com/p/amsoil-premium-protection-10w-40-100-synthetic-motor-oil-amo/?code=AMO1G-EA

of course it would not fix a mechanical wear issue, but they might unstick a ring. I have had that happen on my 4.0 jeep.

 

[KCJeep]

That is low iron for a 4.0 even at 3k.

 

[We're Metals]

VR1 has a solid add pack if you need Zinc. Very nice.

 

[Gene K]

sure


How else does one part of the cylinder wear like that?

Looks just like piston slap wear on a GM LS V8. They have corresponding wear on the piston skirt.