Jeep 4.0, oil question

[TheBlackFish]

I've been reading with great interest since I stumbled over from NAXJA a few weeks ago. I have the infamous 4.0 from a 95 in my 99 Cherokee. The PO said he ran full synth andso I followed suit and I changed the oil about a month ago to QTorque 10w-30 with the larger FL1A Motorcraft filter.

My question is: Do I need a higher ZDDP content for this engine? I've been reading about that and I wonder if I shouldn't give it a blend of the VR1 racing dino and Max-Life Full synth? or should I run a ZDDP additive? I'm really looking to get the most out of this car.

Thanks and I'm glad to be here...

-TBF

 

[Gary Allan]

Keep your fuel system in line and SM oils will do fine in this engine.

Do a UOA at your next oil change to determine what's going on under your current operating conditions. If you truly want to keep this thing as trouble free for as long as possible, it's cheap.


Even a lousy UOA with SM oils is not anything to get upset about. I just ran through a series of SM 5w-20 oil OCI (never EVER spec'd for a 4.0) and, although they weren't stellar, they were nothing to truly alter my use of the oil. Fuel treatments altered wear markers to a significant degree.

I've seen that zddp paranoia thread in the XJ board. That one guy can't get over it. Not that he's totally wrong...just a little more sensitive to it than he needs to be. Something along the lines of spilling a Coke and having some environmentalist screaming at you, "YOU'RE KILLING EARTH WORMS!!!".

 

[fins]

I also have a Jeep with the 4.0..........after reading many of the oil articles I switched to Rotella 15-40 and 5-40 synthetic.
It is suppose to have a higher additive package.

 

[47HO]

What's so "infamous" about the Jeep 4.0? I think its one of the best built engines ever!

 

[KW]

I think they are a very well built engine. They last for many many miles and get pretty good gas mileage too. I really like the 4.0 inline six.

I do believe they do better with a XW40 oil in them over a 30 weight.

 

[sw99]

I personally run 5w30 in mine. I do short trips most of the time and only use the Jeep for maybe 1-2K miles a year. I tried Rotella 15w40 a few times and hated it. It made the jeep feel way too sluggish and the temps here in CO can get a bit chilly in the winter. My current 4.0L seems to love the slightly thinner oil.

 

[TheBlackFish]

I guess I should clarify. This is my first Jeep and I intend to keep it running for as longs as I can. I had been communting 120 miles to work for the last 6 years and had a VW Jetta for that. After my wife and I both got jobs closer to home (5 and 10 mintes respectively), I decided I wanted a 4WD for the winter months. I stumbled across a beauty of a deal on this 99 Cherokee and the engine runs great and I want to keep it that way. Until I found this place, I wasn't very knowledable about oils and fitlers,etc and I used whatever I read in the manual.

Anyways BITOG is now where I get all my oil info (and more!) from and I switched the mini-van to a HM Pennzoil Blend 5w30 and the Jeep is getting full syn QPower 10w30. I plan on switching to a 5w-40 for the winter months.

The point to my ramblings is that I love my new to me Jeep, I like the power of the I6 4.0 and I want to keep it running like a top.

: )

 

[Gary Allan]

Keep the fuel system in line and regular dino 10w-30 works okay. Rotella 5w-40 can be used 12 months ..but, given your shorter mileage, you can surely use a lighter oil in a 30 weight.

After I'm done with some experiments, I'm going to use HDD 5w-30 in mine. I too will keep it forever. There should be a line of parts for the drive train until the sun runs out of hydrogen. In my case, I think the Wrangler will have body parts available forever too.

 

[racer12306]

What would be needed to keep the fuel system in line Gary?

 

[Tones]

FP60 works well in my Volvo. Check it out over in the fuel adds forum.

 

[MarkC]

Keep the air filter changed every 10K miles, plugs, wires, cap & rotor every couple of years.
You don't have to get fancy with the oil on this engine. Plain old 10W30 Havoline works great in mine. Pretty much anything will work fine.

 

[Gary Allan]

Originally Posted By: racer12306
What would be needed to keep the fuel system in line Gary?


Amsoil PI works well. It's a 4000 mile +/- type add. Others that I've had good experience with are Gumout Regane. I didn't see much with Techron ..Seafoam did well with combustion chamber deposits (pinging).

If you can handle "by the tank" adds ..then RLI's fuel system cleaner isn't too expensive @1oz/20 gallon tank..and, although I've never used it, Fuel Power (fp) appears to have good reviews.

Our jeep's injection system is a rather numb speed/density system. It doesn't have any knock sensors ..nor does it have the sophistication to poll each injector to see if it's out of balance with the others. Although highly reliable (simple), it cannot provide an individual pulse width for each injector. Hence you get an "average" O2 rich:lean reading ..which can be varied to a decent degree from one injector to another. Fuel nagged me on my wife's 4.0 over several UOA.

I don't like spending this money to correct for the current lameness of fuel ..but I don't see a viable sensible alternative.