Engine Cleaning - What Oil Weight?

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I have a 1997 Jeep Grand Cherokee Laredo Tsi, 4.0 liter, inline 6cyl. Had the engine replaced a few months ago. The "new" engine has about 168K miles.
New sparks and wires about 4000 miles ago.

I put about .5 quarts of Marvel Mystery Oil in the crankcase a hundred miles ago, and put some in the fuel tank, as well. (I have read the back and forth threads about MMO vs. AutoRX. ARX might be an awesome product, but I need to stick to something I can afford. Money is tight.)

Question: I normally run Valv Maxlife blend, 5w30. For my upcoming OCI, I want to put a full quart of MMO in, so I will substitute 1 quart of oil. I've read MMO can thin out the oil a little.
Should I put Maxlife blend 10w30 in so it's a little thicker?
What is the next step up as far as a "thicker" viscosity? ("Thicker viscosity" probably isn't the right way to say it.)
Is 10w40 the next step past 10w30?

I want to change as few things as possible, so if there is an issue it will be easier to troubleshoot.

I don't consider any of these products (engine cleaners) to be miraculous, though I'm sure they work well. Replacing my engine was a huge amount of $$. I figure if I use MMO (or something similar) every OCI, or every other OCI, and maybe in the gas tank once a month, even if it keeps parts of the engine only 10-15% cleaner than it would be otherwise, that's a win. An extra $6 per OCI and extra $6 once a month in the gas tank is worth it if it allows me to go as long as I can before replacing parts, avoiding knocks, pings, etc.

If you think there's a better engine cleaning product, please let me know (as long as it isn't an MMO vs. ARX shootout.)

Thoughts?

Thank you in advance if you have time to answer.
 
If it was me and I was adding that much MMO to an engine that anecdotally likes a thicker oil, I'd probably bump up to 10w-40 for piece of mind. But that's just me.
smile.gif
 
I would run a decent synthetic oil, maybe the Walmart brand. It will go a good job of cleaning the engine. Kreen is another option.

I would not go the QT of MMO route.

I assume you just got a used engine from salvage yard? What was the engine cost and install cost if you do not mind me asking?

What happened to first engine?
 
Thanks for the replies.

Miller88,
What does "PYB" mean? - Nevermind, found it. Pennzoil Yellow bottle

Drew,
I hadn't heard Jeep GC's liked a thicker oil. The Maxlife blend is supposed to be a synthetic blend, AFAIK. But who knows what the blend % is.
I was thinking the blend was probably a little thinner than a conventional oil. So maybe I'll have to switch to 10w30 for normal use, after the MMO.

Donald,
Could I ask why you wouldn't do a quart of MMO?
Yep, used engine from the junkyard. The engine was about $1700 and the total for everything was $2900.
As far as what was wrong w/ the original, I had taken it in because of a noise coming from the engine block. (Can't recall exact nature of the noise now.)
The shop said that they figured it was probably the rod bearings going out. And that I should either look at a new Jeep or new engine.
Oh, and FWIW, this wasn't a dealership. It was a smaller chain shop that has worked on the Jeep many times (I got it at 198,200 miles, and it needed a lot of work.)

I don't honestly know what rod bearings are.
 
Last edited:
Originally Posted By: niero
Thanks for the replies.

Miller88,
What does "PYB" mean? - Nevermind, found it. Pennzoil Yellow bottle

Drew,
I hadn't heard Jeep GC's liked a thicker oil. The Maxlife blend is supposed to be a synthetic blend, AFAIK. But who knows what the blend % is.
I was thinking the blend was probably a little thinner than a conventional oil. So maybe I'll have to switch to 10w30 for normal use, after the MMO.

Donald,
Could I ask why you wouldn't do a quart of MMO?
Yep, used engine from the junkyard. The engine was about $1700 and the total for everything was $2900.
As far as what was wrong w/ the original, I had taken it in because of a noise coming from the engine block. (Can't recall exact nature of the noise now.)
The shop said that they figured it was probably the rod bearings going out. And that I should either look at a new Jeep or new engine.
Oh, and FWIW, this wasn't a dealership. It was a smaller chain shop that has worked on the Jeep many times (I got it at 198,200 miles, and it needed a lot of work.)

I don't honestly know what rod bearings are.


The rod connects the piston to the crankshaft. its got a wrist pin on top and rod bearing on the crankshaft.

I paid about what you did for the engine, but I got a reman from Marshall Engines via RockAuto. With the install cost, you would have to give me a salvage engine before I would consider it.

I think a QT of MMO is too high a % of the total sump capacity. Its a cleaner not a great oil. I would not want 20% of my total oil to not be a good oil. Try a cup. Or Walmart synthetic.

You can go to Rotella T or T6, both great oils, but you will loose maybe 1.5 MPG. I am not sure I would say they like thick oils, but they do OK with them. I have gone back to 10W30 from T6 5W40.
 
Mobil 1 High Mileage 5-30 and a 1/2 bottle MOS2. The 2nd oci M1HM and the other half of MOS2
 
Run any name brand synthetic 5/10w30 and you Will clean it up in time. Pennzoil comes to mind.
 
Originally Posted By: 285south
Mobil 1 High Mileage 5-30 and a 1/2 bottle MOS2. The 2nd oci M1HM and the other half of MOS2




Why the mos2. In my experience using mos2 unless the engine is clean,and used as directed it doesn't do a whole lot.
I've used mos2 in all my air compressors and generators,countless cars and trucks and a diesel or 2 and I can say without any doubts whatsoever if not used as directed it won't accomplish anything,and if the internals aren't clean it won't plate,so I suggest following the directions as far as concentration.
I can say for certain that after the first full strength application half strength can be used to maintain the plating effect however half strength primary applications really doesn't do anything in my experience.

Motor oil saver is an ester and will clean an engines internals without harsh chemicals however I do like solvents for cleaning up engines because they will flash off,cleaning the pcv and intake tract to a point.
I've had good luck using seafoam.mmo,stp oil additives for cleaning internals. Leave it for the entire interval. Within 1000 miles the solvents will flash off leaving the light carrier oil and whatever ingredients are included as cleaning agents.
Today's oil additives that can be bought over the counter really aren't that strong or dangerous to use. Basically idiot proof.
 
Do you have reason to suspect that the engine needs cleaning?
If not, just use any decent oil on reasonable drain intervals and you'll be doing all you can to protect the engine.
Any recent API spec oil will keep an engine clean as long as it isn't run too long. How long will depend upon the use you make of the machine.
If you do decide to run a full quart of MMO, I'd make the rest of the oil a 10W-40.
 
Originally Posted By: fdcg27
Do you have reason to suspect that the engine needs cleaning?
If not, just use any decent oil on reasonable drain intervals and you'll be doing all you can to protect the engine.
Any recent API spec oil will keep an engine clean as long as it isn't run too long. How long will depend upon the use you make of the machine.
If you do decide to run a full quart of MMO, I'd make the rest of the oil a 10W-40.


Good info, or if the guy lives in a colder climate he can use the Marvel in the winter, if he can wait. That has been mentioned a few times by a long time user in old threads I've been reading. I use it that way too, [when I needed it] but honestly it doesn't matter.
 
Originally Posted By: fdcg27
Do you have reason to suspect that the engine needs cleaning?
If not, just use any decent oil on reasonable drain intervals and you'll be doing all you can to protect the engine.
Any recent API spec oil will keep an engine clean as long as it isn't run too long. How long will depend upon the use you make of the machine.
If you do decide to run a full quart of MMO, I'd make the rest of the oil a 10W-40.


If you have hard evidence you have sludge in your engine, try this from Rislone:

Rislone Engine Treatment

It has special (slow) cleaners and additional friction modifiers. It is a 5W20 so don't run the mix over 500 miles.


If you do not have any evidence of sludge, just run a synthetic 10W30 like Pennzoil Platinum.

But since you said

Quote:
I have a 1997 Jeep Grand Cherokee Laredo Tsi, 4.0 liter, inline 6cyl. Had the engine replaced a few months ago. The "new" engine has about 168K miles. New sparks and wires about 4000 miles ago.


How can you put 168k on an engine you just replaced a few months ago?
 
Last edited:
Originally Posted By: MolaKule
Originally Posted By: fdcg27
Do you have reason to suspect that the engine needs cleaning?
If not, just use any decent oil on reasonable drain intervals and you'll be doing all you can to protect the engine.
Any recent API spec oil will keep an engine clean as long as it isn't run too long. How long will depend upon the use you make of the machine.
If you do decide to run a full quart of MMO, I'd make the rest of the oil a 10W-40.


If you have hard evidence you have sludge in your engine, try this from Rislone:

Rislone Engine Treatment

It has special (slow) cleaners and additional friction modifiers. It is a 5W20 so don't run the mix over 500 miles.


If you do not have any evidence of sludge, just run a synthetic 10W30 like Pennzoil Platinum.

But since you said

Quote:
I have a 1997 Jeep Grand Cherokee Laredo Tsi, 4.0 liter, inline 6cyl. Had the engine replaced a few months ago. The "new" engine has about 168K miles. New sparks and wires about 4000 miles ago.


How can you put 168k on an engine you just replaced a few months ago?



I meant that the engine that was put in a few months ago has now has about 168,000 to 170,000 miles on it. It was above 160K miles when it was put in as it was bought from a salvage yard. It was literally the only one we could get our hands on at the time.
 
Originally Posted By: fdcg27
Do you have reason to suspect that the engine needs cleaning?
If not, just use any decent oil on reasonable drain intervals and you'll be doing all you can to protect the engine.
Any recent API spec oil will keep an engine clean as long as it isn't run too long. How long will depend upon the use you make of the machine.
If you do decide to run a full quart of MMO, I'd make the rest of the oil a 10W-40.



I don't have "direct" evidence that the engine needs cleaning. By that I mean, I haven't taken off the valve cover to look. I'm not mechanically inclined, and don't have the tools.

I'm going the engine cleaning route for a couple reasons:
1) I don't know the history of the engine and so a thorough cleaning over a couple OCI's isn't going to hurt.
2) I want this engine to last as long as possible, so even if it only results in parts of the engine being 10% cleaner than they otherwise would be, I still consider that a win. MMO is not a risky product in that if I don't follow directions to the letter I could ruin my engine. (Obviously, doing something stupid like pouring 2 quarts of MMO in and not enough oil or something could be harmful, but I think you get my drift.)
3) Judging by what people have been saying, I think I've been using a pretty good oil, as I always use the Valv Maxlife, which is said to have a lot of detergents. Something I could do to improve is maybe request the fully synthetic version, rather than the blend. But this is an old engine so I'm not sure if that's a good idea.

I'm hearing a lot of good things about Pennzoil Platinum, but right now I usually have the car shop or Valvoline Instant Oil Change do the oil changes. If I'm buying expensive oil I'm not sure how much I would save by doing it myself.
 
I would run 80% Delvac 1300 15w40 (because it's cheap - Under $12 a gallon at WM) and 20% MMO. That seems to really clean the internals. I am currently doing this on my varnished 1ZZFE engine.
 
If using MMO in that engine, I'd imediatelly drop that pan down (after drainage, of course) to clean the pickup screen, or, your lottery.
 
Last edited:
Originally Posted By: sprintman
I'd run a thicker oil fwiw. 40W70 would be about right...............


Never knew they ran that thick. What kind of vehicle is it in? What made you go to that weight?
 
Originally Posted By: MolaKule

If you have hard evidence you have sludge in your engine, try this from Rislone:

Rislone Engine Treatment

It has special (slow) cleaners and additional friction modifiers. It is a 5W20 so don't run the mix over 500 miles.


Whoa!? The Rislone is actually 5w-20? I actually would have thought it was thinner. If you don't mind me asking, how do you know? Did you run tests on it?
 
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