Used to always just use a good old can of motor flush in the can from gunk and never seen a problem I know of always blew up my old rides any how lol . In my jeep I have done one oil change seems I got it dont drive her as much as I would like and all the down time due to my tranny bs I have been threw . I used BG in it then . It has had dam near every BG thing ya can do to it . And I never noticed any diffrince from any of it . Not even a 1/2 mpg before parked it this last time I dint know maby dint drive it a nuff to tell maby 1000mls or so . I would like to know more about the tranny fluid trick . I had a old German guy live next to me as a kid and he used to rebuild outboards and showed me how to use it to flush out carbs and heads buy poring it in and rev the crap out it and all the yummy wight clouds that come out . Can be done to are zjs with the throttle body faceting up . My old rides where always snapper after I did it and would do it about every 10k

 

I've heard about the atf working well, I also heard that it likes to eat gaskets. Never tried the MMO or sea foam for oil treatment.

Years ago I bought a 91 Ramcharger that hadn't had an oil change in a very long time. There was an oil soaked dish towel under the hood along with a quart of cheap gas station oil. The oil filter also had a date written on it from 3 years before I bought the truck. First thing I did was replace the valve cover gaskets then change the oil. The rockers were covered in a thick sludge. I put penzoil high mileage in it. I drive a fair amount and probably did 5 oil changes to it in about a year. After this year of driving I decided to put an "RV" cam in it. Off came the valve covers again and I couldn't believe how clean the rockers were. They weren't shiny but all the sludge was gone. You have to drop the pan to get the timing cover off and there wasn't anything clogging the oil pump or laying at the bottom of the pan either.

 

I did the sea foam cleaning on my last oil change...I didn't use the whole recommended amount, but I put about 200 miles on it and immediately dropped the oil and it was about as black as coal...started as nice golden Mobil1

 

I haven't seen a bad post in this thread yet, but I want to add a thing or two too it.

1) ATF was borne of 30w oil with an additive package (detergents and friction modifiers, or "oil friendly soap + anti clutch chatter juice"). The big three didn't get together and come up with a special juice to run in a new type of transmission, they each developed a new type of transmission to work with a very common and available type of juice. I could give you a history lesson on why, but in short, ATF will not hurt your engine "per se". ATF MIGHT eat your gaskets and seals though, but it is at it's base, 30w oil and won't cease a piston.

2) Marvel Mystery Oil was SPECIFICALLY MARKETED TO CLEAN THE MARVEL CARBURETOR. The Marvel carb was a turd. That's why you've never heard of it. I'm not joking. MMO is basically 30w oil mixed with naphtha, so it burns like gas and lubes like WD-40. Use it as you see fit!

 

Nopa, you forgot to give your preference!

 

I apologize Gibs, I'm not trying to be coy. I'm just not a fan of snake oil. Don't get me wrong, I'm not above dumping a can of somethin-somethin in a filler tube when I think it'll help. My AMC engines all get a bottle of STP or Oreilly's oil treatment at oil change time since oil doesn't come with ZDDP anymore because it harms catalytic converters, but is necessary for flat tappet cams.

When it comes to cleaning "gunk" out of your engine, I spend my money on gaskets to drop the pan and pull the rocker covers and see what "gunk" is really there. Gunk can exist, I know it. I pulled the covers on a running AMC 360 once and found chunky gunky build up essentially cast in the shape of the rocker covers. If that had started to break up it would've plugged a filter in minutes. I realized that engine flushes present more risk than they do benefit.

Professionally, I'm an engineer and I subscribe to the scientific method. "Bob the oil guy"s website can be harsh and it can be very subjective in it's recommendations but it DOES do a pretty good job of documenting data with supporting reference, being both clinical and observed. I consider it a viable reference when it comes to engine maintenance.

As I said before I know "gunk" is real, I've seen it. From BTOG I've learned that the two biggest causes of "gunk" is failure to perform proper maintenance intervals, and paraffin based conventional oils (like Pennsoil USED to be).

The problem that directly relates to your question is that without opening up the engine there's no way to know how much gunk there is. If it's superficial, then an engine cleaning agent will work at the expense of the oil and oil filter in service. If it's MORE than superficial, then releasing it into the engine by means of a cleaning agent runs the risk of destroying the engine by plugging the filter and forcing the over pressure bypass to allow all the released gunk in the oil flow through the engine.

The only way to be sure it so open up the engine and look, and at that point you can de-gunk the engine manually.

 

Seafoam IMO is the best, The military use to use it. Another old farmers trick is to mix either kerosene or diesel fuel in the crank case with the oil and let run at high idle for 15 minutes, drain, change filter and put new oil in. I have done that myself on a Subaru that had over 200k on it that was neglected on oil changes. After doing that flush the system was really clean.

 

I've used Seafoam in the past on a Rodeo. Didn't really notice any change in performance for better or worst. Truck continued to run great!

 

ATF doesn't have near the detergent levels of modern oils

MMO and seafoam i mostly use for fuel additives (and more in small engines than my vehicle).. i did seafoam in the oil once and yes the oil came out black as can be but i can't really speak for the level of cleaning it did

a few short (but not too short... maybe cut 500-1000 miles off your normal) OCIs with quality oil will do more than most additives

Auto-RX seems to have a lot of love at the bob is the oil guy forums... not cheap though

 

I have the best way to clean your crankcase. Ok, so every 3,000 miles, drain all your oil. Next Replace the oil filter. From there add the oil you drained. Rinse and repeat. Your wasting your time and money doing anything else now a days. This isnt the 60s and 70s, modern oil is great. Modern engines are also not so bad, they arent as good as the oil, but they still do well.

My vote, none of the above. Go take the money you where going to spend on above products and after your oil change grab a burger, taco, or shwarma. Whatever you like

 

Now now my friends. The question wasnt if its worth spending the money, but rather which produces the better results. That's the funny thing about reading. If you bothered to learn how to do it properly, then maybe you wouldnt be answering a question that wasn't asked. Now lets try to stay on topic shall we?

 

i use seafom occasionally on all my jeeps, drop some in the intake, fire it up and watch the smoke show for 10-15 mins, has helped in the past....

 

I've used seafoam in the crankcase in many of my cars in the past, I'm not entirely sure how much good it did, but it didn't CAUSE any problems. ATF will clean well also as I have used that on some GM vehicles after doing intake gaskets, again not sure how much it actually did but it didn't CAUSE any problems.

I think if you are looking for the easiest, just dump some seafoam in a day or so before your oil change and that will be what you desire. The other thing people tend to forget about seafoam is that it will burn away quickly in oil after it is at operating temperature. So even if you don't change it immediatly, oh well.

 

I'm using brake fluid. 0.5 litres in the oil, let the engine idle for 15minutes, then drain oil, and pour fresh oil in with a new filter. After this, I'm only using Eneos, 10w40 oil. The oil is still golden after 3000km after the change.

 

Nopa, I think you bring up some valid points. I suppose the fault is my own for not clearly specifying my use for this thread. I have noticed of the years my Jeep has been feeling a bit tired and lacking in her power and acceleration. I recently replaced the gasket on my valve cover and it didn't appear too too bad as far as gunk. I'm hoping that by simply using a cleaner it may clean out any power robbing elements that have built up over the years.

While there's no real signs of a problem worth doing a full overhaul of my engine for, I'm simply looking to add a procedure to my typical vehicle maintenance procedure that may help alleviate some of the poor performance issues I'm having. While I have never missed a service interval, the previous owner clearly neglected the maintenance on the car. Perhaps this will shed some light and help give your opinion some direction?

 

Gotcha!

I hate it when people post up "research blah blah blah", so instead of turning you loose with google I'm just going to try and give you the ClifNotes on dynamic efficiency (usually called "volumetric efficiency" in the automotive world).

The power of your engine is determined by:

CP (caloric potential of a given unit of fuel/air mixture) = Horse Power (distance moved x unit weight / unit time) PLUS T^1 (thermal energy, or wasted heat).

I'd like to point out that what you see there is foot pounds, not to be confused with pound feet ( a torque measurement, or rotational force). I'm leaving out the incline and some other details because you're not going to be doing this math, this is purely for conceptual understanding.

So, if the equation relating to your engine CP = HP + T^1, HP has decreased, then either your CP has dropped or your T^1 has gone up.

Causes for CP dropping could be incomplete combustion due to fouled plugs, dirty injectors, sloppy distributor or crank position sensor, or faulty MAF or O2 sensor to name a few. Or, more likely with the 4.0l, worn rings allowing that energy to slip past the piston into the crankcase instead of doing the work of moving the piston down; or worn lifters not maintaining lift on the cam so less CP gets into the cylinder.

Causes of T^1 increasing would be improper ignition timing (or less likely an increase in internal friction). Some symptoms of decreased CP are manifested by also increasing T^1, such as improper fuel/air mixture due to failed MAF or O2 sensor. If your OBDII 1997 4.0l isn't throwing codes, I think you can stick with CP dropping and start with a compression test of the cylinders to determine just how worn your engine is. Once you know that you can make a more informed decision about what to investigate next or what to do to extend the life of the engine.

 

Holy ****. What do you do for a profession? You seem more than well versed in this. Are you an engineer? I'll be sure to have a compression test done. I do recall a few years ago however my Jeep was running extremely rough and claimed an 02 sensor or MAF sensor was bad (due to Running too rich if I recall, don't call me on it though) However, the issue resolved itself before I got a chance to determine the cause of the issue. I recently replaced the 02 sensor in the Cat (I replaced the Cat with a Magnaflow and I couldnt get the old sensor out) Think this has anything to do with the issue? No codes for well over a year now.....

 

i say rislone. i did this on my cherokee a while back and it worked flawlessly. i had so much gunk when i took off my valve cover there was a perfect inpression of the lifters in ... something caked to the cover. i scraped what i could and cleaned it...put it back on. then i drained the oil and replaced one quart with rislone. ran it for 300 miles and changed the oil. took the valve cover off and it was metal colored again, springs were clean and lifters were spotless. tapping was gone, and engine ran so much smoother.

any time i have dirty engine issues, i use rislone

 

Personally, I SeaFoam every 5 oil changes, with only using 1/3 of the bottle, and running it for 50-100 miles, drain, fill, and change the filter. I'll run 4qt of whatever cheap 10w-30 I can get, and 1qt of Rotella diesel 10w-30. Dodge mechanic told me the bottom end of my 5.2 was perfect and to keep doing whatever I was doing.

 

Same here. I use STP in my 62 Chrysler,and my 73 Fiat every oil change.