Want to use MMO to clean neglected engine.Confused

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Last year I purchased a 2001 Infiniti QX4 (engine: V6 VQ35DE) with 125,000 miles. I believe the engine was not properly taken care of regularly and would like to clean it safely the best I can. I changed the oil from whatever was in there to Mobil 1 High Mileage 5W-30 FULL Synthetic with FRAM ToughGuard filter and ran it for 1500 miles. At 126,500 I changed the oil again with the same FULL Synthetic oil and filter. Now 3,000 miles later at 129,500 I just changed the oil again.

The question is: Should I switch back to Conventional (Mobil 1 5w-30 conventional) on the next few changes while using MMO? How many changes with MMO should I use before I can revert back to my Mobil 1 5w-30 High Mileage Synthetic? I plan on using 20% MMO in the crankcase? Would this be considered too aggressive?

Any thoughts on this would be helpful. I'm 99% sure I'm overthinking and should just do it already.

The main things i want to accomplish:
1) Clean-up any neglect as I don't have service records and suspect little maintenance
2) Fix a random rattle at cold start-ups. Believe this is tied to lack of oil pressure in the timing chain tensioner which could be result of sludge/build-up

Also, I purchased an older Honda Civic 1991 and plan on doing something similar. It is extremely low mileage for it's age (124,000 miles) and I want to clean up anything that might have resulted with it sitting for long and rarely being driven.

Thank you!
 
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Originally Posted By: Miller88
run short intervals with a good synthetic ... basically what you have been doing.

Sure, but not THAT short. Unless it's a sludge monster from the 70s, there is nothing that will happen in 1500 miles in a recent engine that will require replacing the oil or filter that soon.

Synthetic helps clean varnish and sludge, yes, but it's not a solvent. It's sill just motor oil.
 
Originally Posted By: Legend11
The question is: Should I switch back to Conventional (Mobil 1 5w-30 conventional) on the next few changes while using MMO? How many changes with MMO should I use before I can revert back to my Mobil 1 5w-30 High Mileage Synthetic? I plan on using 20% MMO in the crankcase? Would this be considered too aggressive?

20% MMO would be fine for maybe the last 500 miles of an OCI. I certainly would not run it for the full OCI.

MMO may be an 'oil' but it's not much a lubricant and it'll thin out whatever oil you add it to reducing its ability to do its job. It does help an oil's cleaning ability but people have had mixed results depending on how they used it and what they used it in. It did help the oil consumption problem on my wife's Corolla and helped get rid of some valvetrain noise, but YMMV.
 
I like the idea of running it for a little bit of time. Even if it's more "mental", I'll feel better knowing I'm trying something to clean-up my engine a little. I also ready online that using the Mobil 1 High Mileage Oil every 3000 will accomplish the same thing as the detergents in the oil will slowly clean the engine. So hopefully overtime the engine will be improved. Of course, I'm probably searching for a silver bullet which doesn't exist.
 
How about running the MMO with the 5w30 Mobil 1 High Mileage Full Synthetic? Would it be wise to switch to conventional during this cleaning?
 
The VQ35DE is known for timing chain problems, your possibly dealing with a broken chain guide, it has nothing to do with oil pressure at the tensioner.
There are 2 small cover that you can remove to inspect the tensioner and guide on the pass side of the engine and one on the drivers side to inspect the smaller guide.

There are 3 tensioners, 5 guides and 3 chains. 2 short chains with tensioners and small guides, one long chain with one tensioner and 2 long guides, one upper and one at the tesnioner and another smaller one on the drivers side.
The guide on the long chain tensioner breaks allowing the tensioner to fully expand without tensioning the chain.
You need to look into this right away, it could cost you the engine. It would be very rare that one sticks on these. Better safe than sorry.

As fr as cleaning it goes, just change the oil and filter, these engines like Mobil 1 0w40 which in itself has good cleaning abilities.

This is what it looks like. Don't buy this cheap junk kit its just for illustration.

Tining Chain Kit
 
Thank you for the in depth reply. If I recall correctly, I did read an article/post on the timing guide being a possible cause for the noise. Perhaps I'll just stick with my current regimen and investigate this issue. On a side note, you recommended Mobil 1 0w40 viscosity; why not stick with the recommended 5w30 in the owner's manual? Thanks again
 
Originally Posted By: Legend11
Thank you for the in depth reply. If I recall correctly, I did read an article/post on the timing guide being a possible cause for the noise. Perhaps I'll just stick with my current regimen and investigate this issue. On a side note, you recommended Mobil 1 0w40 viscosity; why not stick with the recommended 5w30 in the owner's manual? Thanks again


You won't go wrong with the 0w40. If you want to get it clean just do a 5000 mile OCI and over time it will clean the engine. Pennzoil Platinum also cleans well. I use the 5w30 PP in my cars.
 
Originally Posted By: Miller88
Skip the mmo, run short intervals with a good synthetic ... basically what you have been doing.


+1 on skipping the MMO and using quality synthetic oil.

Until you pull a valve cover and have a look, you really do not know how clean or dirty it is.
 
Its up to you what you want to do, but if your positive about using MMO why not try it with a high detergent diesel oil?

Rotella seems to be the crowd favorite. The extra detergent and dispersants might aid in cleaning up any problem.

From past experience I will say in my vehicles MMO only lasts roughly 500 miles. That's the point where I see a noticeable drop in oil level.
 
Originally Posted By: Legend11
I'll just stick with my current regimen and investigate this issue .... with Mobil 1 0W-40 [as Trav suggested].


Great advice!

Doing a few shorter LOF changes while investigating the excessive wear issues on the 3 timing chains and 5 guides is prudent.

Hope you didn't get burned on the timing chain / guide issue; perhaps that's one main reason why the previous owner got rid of the vehicle before it was too late.
 
Use whatever oil you want, synthetic or conventional is irrelevant. Add MMO or riselone and do a bunch of 3k OCIs. I would also use a 5 minute motor flush. You will have that thing clean in no time.
 
But you don't even know if the engine is "dirty" or needs cleaning, right? Have you pulled a valve cover to look? That's the easiest first step to check. If you don't check then how do you know it needs anything or if you are doing anything with the cleaners?

So many times people say they "think" they need something but don't know. Then after running Cleaner X, they have no idea if it did anything, or if it even needed it in the first place.
 
It's dirty?

Originally Posted By: jk_636
Use whatever oil you want, synthetic or conventional is irrelevant. Add MMO or riselone and do a bunch of 3k OCIs. I would also use a 5 minute motor flush. You will have that thing clean in no time.
 
Neglected vehicles are always dirty. Nature of the beast. OP don't take my word for it, go to harbor freight and buy a cheap snake camera. Look at your piston heads and inside the crankcase. Then flush it with the 5 minute motor flush and use good oil with MMO or 1 quart of riselone. I would even add some Royal purple max clean or other fuel system cleaner to work on the injectors and any remaining corrosion on the position head or cylinders. Do a couple more short OCIs and then look again. You would be amazed how much cleaner the motor will be and how much smoother it will run.
 
Originally Posted By: Trav
You might find this interesting. I have the FSM for this engine on DVD if you need anything.

http://www.nissanclub.com/forums/2002-20...ming-chain.html



Trav, i spent a few more hours tonight reading up on my exact problem and you hit it right on the nose. Thank you! It looks like this job will have to be done as soon as I get a chance. The only thing I'm not sure of is if all VQ35DE engines will eventually have this problem or if there is specific production lot that does; perhaps just neglected VQ35DE's? Seems like some well maintained vehicles are having this problem too.

Also, hoping Nissan has some updated parts so this won't happen again. Now, I'm not sure if I should just focus on replacing the guides and tensioner or replace all 3 chains and hardware, etc... Looks like a big job. I have experience changing timing belts on my older Honda Civics, but this looks like new territory.

Thank you again
 
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Originally Posted By: Trav
You might find this interesting. I have the FSM for this engine on DVD if you need anything.

http://www.nissanclub.com/forums/2002-20...ming-chain.html



Also, considering tackling this myself (not a mechanic, but have done a lot of work... usually takes me 10x as long as a mechanic with 10x as much swearing lol). If you have any guides/service manuals on this that will be awesome. I may consider having a shop do this though.
 
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