Fluid Film is great stuff!

As easy as it is to pop the valve cover off the 4.0, I'm going to do the MMO soak as soon as mine start clattering again. It will happen again sooner or later, and the noise really annoys me. Sticky HLAs will typically wear cam lobes over time.

I know I should do it. Been a long year and like I said I am tired. Fluid Film is great stuff. Been using it for the last 3 years. Usually go to my friends house use his gun kit and compressor. But this year I bought a decent compressor and the gun kit.

I need to look into that. I've just been using the cans.

Ya. I don't think it's a good idea to run MMO in the oil. Not after my experience anyway. If so maybe just run it a couple days then change it. Not sure if there would be any benefit or not. I think my problem even with only replacing half a quart, was that it made my oil too thin.
Only reason I ran it in the first place was because of a misfire I've had in one cylinder. Already verified by a leakdown test that one or both of the valves not completely closing or sealing. Didn't check if it was intake or exhaust. I've tried several other ways to clean my valves just hoping it was carbon buildup or something. Mystery oil in the engine didn't help either. Probably not just carbon. Oh well.

If you have a compressor then spend the money for the gun kit. The thing I like most about it is one of the hoses. It is just like the wand you can buy for the spray cans. Great for inside the uni-body. I use about a 1/2 gallon when I do my Jeep. But I go to town. Figure I spend about $35 for a gallon. So $18 for one application. What is that in cans? 2 maybe. Pretty sure you are not doing a whole Jeep with 2 cans.

I wouldn't either, but people have been doing it for many, many years (since 1923). I've never read or heard about anything bad coming from it. It will slightly reduce viscosity, but only by minimal amounts if the directions are followed. The small amount of solvents in MMO (25% according to the NTSB) will burn off quickly after a few heat cycles, so they won't stay in circulation for the duration of the oil change interval.

I only use it when needed to free up HLAs, and my method outlined above only requires about 8oz added to 6 quarts of oil, which would make up less than 5% of the oil in the crankcase.

Been using it for years for certain applications. It's the only additive I use. Following the directions I run it through my 2 vehicles fuel systems twice a yr. Sept. and March.

Just about all high mileage 4.0s get lifter tick when cold. I am running Castrol 15w40 diesel oil in mine and I still get the lifter tick on startup but it goes away in a couple of minutes. The 15w40 also increased my oil pressure significantly over the 10w30 I was using. At idle when warm it used to drop to 5-6 psi now it stays around 20.

My 99 with 180k miles had a little noise, and the 4.0 in my wifes '04 WJ is noisy too. I like napa gold or mopar filters. Ive tried a few different brands in the wifes jeep and so far is a little quieter with Napa 1085 filter and Havoline high mileage 10w30. Mine quieted right down at last oil change with Napa's big 1515 filter and Delo 10w30. I like that 1515/Delo combo, probably wont stray from that for a while. Have you tried running a can of seafoam in the oil for 20 or 30 minutes before changing the oil? Or..adding a quart of trans fluid to the oil and letting it idle for 30 minutes before oil change, to help clean things up a bit?

Yes, 4.0L engines are noisy. Mine has 293,000 miles on it.

But it runs quieter than in the past.

I use Rotella T6 full synthetic and go 7500 miles between changes.

At oil change I have recently been adding 5 qt Rotella and 1 qt ATF.

Seems the ATF burns through in about 4000 miles though.

Then it is time to add more Rotella.

Engine no longer sounds like an old Mercedes diesel. Does not leak. Runs strong.

Also, check for exhaust leaks. They can be "ticky" on cold start up and go away soon. Remove the air box and tape a 2" strip of tissue paper on the end of stick. Poke it around the manifold. If you have a leak, the tissue will be waving like a flag!

I have removed and welded up the ATP replacement manifold TWO TIMES in the past year.

Edit: BTW, Rotella T6 changed formula a while ago. And there seem to be not good deals on it anymore. Hope it is still as good was it was. But it is expensive now. I bought the huge 2.5 gallon jug last time just to try and save a bit.

"At oil change I have recently been adding 5 qt Rotella and 1 qt ATF.

Interesting, you have a 4.0 with a 6 quart system?

I thought all 4 liters were 6 quarts with filter change. Isn't yours?

'Well they say you learn something every day, and I just learned I do NOT have a 5 quart system like I thought all these years.

6 seems to be the correct response.
Funny, when I buy that container of oil at wally world, it seems to top it right off after a change and filter, and I always thought there were 5 quarts in that jug.

Heck my buddies 389 Pontiac took 6 quarts.

Well, no one seems worried about the switch to synthetic, so I think I'll ride it out and see how it behaves. I have been wanting to do the valve cover seal for a while, will be my first time opening it up. Anything I should be looking for while it's open? Think I may try the MMO trick mentioned above while I'm in there.

I have never heard of Fluid Film, but as mine is just starting to rust, I'm very interested in that.

The lines on the dipstick aren't exactly accurate. It will look slightly overfilled usually at 6 quarts. I use a larger-capacity filter (Motorcraft FL-1A or equivalent), pour in 6 quarts and it's right on the full line.

The owner's manual and service manual both state 6 quarts.