Moly offset lower ZDDP?

[KCJeep]

I've been using Rotella in my Jeep ever since I got it, for the ZDDP and heavy cleaning agents (mine was a tad neglected by the PO). For the first time last week I put Pennzoil YB 5w30 in it for the winter months. It runs quieter on the Pennzoil than it's ever run. This is the Jeep 4.0 I-6.

I know PYB is loaded with moly, does it offset the lower ZDDP in current PCMO? I would think a quieter engine is certainly getting enough lubrication...or maybe the 4.0 doesn't really need the higher ZDDP it's often touted to need?

I don't know but it's got me reconsidering my oil choices for the Jeep 4.0.

Thoughts?

 

[JAG]

MoDTC (a type of "moly" often used in motor oils) works synergistically with ZDDP, so that combination does allow ZDDP to be lowered while retaining or improving wear protection vs. higher ZDDP oil with no such moly. It also reduces the coefficient of friction in sliding contacts but this effect degrades during the oil change interval.

 

[MrRPM]

what weight of rotella did you use? if it was 15w40 that might be another reason for the 5w30 to be quieter. atleast till the oils are very hot.

 

[KCJeep]

I've tried but my Jeep doesn't seem to care for the 40 weights, so I've been using 10w30 Rotella which has worked very well. I'm sure I'll use it again as I still have a few jugs, but I put the 5w30 PYB in for the cold months and got quite a surprise.

The 5w30 PYB is quieter at all running stages, even hot. All I could figure was it must be the moly. It's never been this quiet since I've had it.

 

[shpankey]

Seen this mentioned several times now. I think it may have some merit.

 

[Boss302fan]

Could also use 10W30 PYB... Although Rotella 10W30 is used by many in your engine... Rotella is a very robust oil.

Remember in cold weather that a 5W30 is going to initially flow better at startup then a 10W30...

 

[84zmyfavorite]

My 99 Cherokees reBuilt 4.0 has Pennzoil 10w30 in it currently, and yes, it is a quiet, smooth running 4.0. I believe Jeep 4.0s like PYB, 5w30 like you used for Cold weather, and 10w30 for pretty much any time of the year IMO.

 

[MrRPM]

very interesting, i might have to try it this summer in my 4.0

 

[wtd]

I recently changed the oil in one of my 92 Cavaliers with the 2.2L 4cly and used 5w30 PYB and the engine was quieter than it was before using Valvoline.

Wayne