Bad stiction issues 7.3 powerstroke mmo?
- Thread starter don1911
- Start date
That's a great idea. I will run redline next oil change with hotshots stiction eliminator in it. I am running hotshots right now and it's eliminated 75% of the problem but sometimes I get a bad cold start rough not running right low power smoke. I get on the road and floor it and eventually it runs right
Thank you! I emailed mmo about this question they have declined to respond
I assume the answer to the OPs question would be a high quality diesel fuel additive. I was pointing out MMO is not a high quality diesel fuel additive.
The fuel injectors on a 7.3 powerstroke are powered by high pressure engine oil. I was asking if it was safe to use MMO in the engine oil!
MMO is not a high quality oil additive, either. Smells good, though. It's mostly cheap base oil and Stoddard solvent (paint thinner) with dye and odorant.
I cannot see MMO used anywhere where lubrication it's the priority. I think it's never a good idea to add a solvent to engine motor oil. Unless you can just turn over the engine with solvent added (not start) then drain and fill with engine oil before starting.
Can't the injectors be removed and soaked in a solvent.
Aren't the pickups with a 7.3 Powerstroke engines getting old even if the engine runs fine? You have interior, frame, body, transmission and drive train.
I have a 2015 that has the 6.7 PSD. It's been rust proofed several times but slowly getting old. Radio works but cannot see the display very easily. Other little things. Has 168K. I think the value is $8K or $9K. But if transmission went that could be $3K maybe more. At 72 yr old, do I want to dump $80K on a new one?
CleanSump
Site Donor 2026
The wintergreen oil gives it the scent, but wintergreen oil also is to condition old rubber and dissolve corrosion on metal. MMO smells like Ballistol, another product I find is mediocre at best.
The HEUI injector is a unique piece. It needs electrical power, fuel pressure, and high pressure oil to function. Any one of these could be lacking. Typically, the 7.3 is not as affected by oil issues as the 6.0. A few short oil changes and diligent fuel filter maintenance (draining, cleaning the fuel bowl, and replacing the filter with a Motorcraft unit will do you some good.
At least 50% of the running issues I've seen on old diesels trace back to a dirty fuel filter.
At least 50% of the running issues I've seen on old diesels trace back to a dirty fuel filter.
- Joined
- Mar 4, 2026
- Messages
- 148
MMO is not going to help.
You should have done a UOA after the addition of Stiction Eliminator I bet the results might shock you. It is ester based and does not play nice with every oil.
Cost wise shimming is the best solution. Then sending yours out to be refurbished is #2. Cost no issue replacing the injectors is the answer #3. How much longer you expect to drive this has to be included as well given the insane replacement cost if this truck is no longer making you money!
Hot Shots make a PAO engine oil. I have seen it on Amazon that is about as available as it get's.
You should have done a UOA after the addition of Stiction Eliminator I bet the results might shock you. It is ester based and does not play nice with every oil.
Cost wise shimming is the best solution. Then sending yours out to be refurbished is #2. Cost no issue replacing the injectors is the answer #3. How much longer you expect to drive this has to be included as well given the insane replacement cost if this truck is no longer making you money!
Hot Shots make a PAO engine oil. I have seen it on Amazon that is about as available as it get's.
- Joined
- Mar 4, 2026
- Messages
- 148
What does your 7.3 hold for oil something like 3 gallons correct? Sorry I am used to much bigger deisels. You might try Schaeffers 131@ 1oz per quart of motor oil. The only amendment to the instruction I would make is that the first time you do this only let the engine idle for 4 hours with it in it then drain. Next time repeat but add it 200 miles before the oil change. Next time 500 miles before the oil change.
Why so cautious. It works very well and while I know that idling is terrible and it messes with regen you have a 300K miles on this and deisel generates a lot of soot. You do not want to over over load the oil filter with soot from 300K miles of use.
Schaeffers recomends 1oz per quart 500 miles before you change your oil. My experince with using this on older tractors, deisels and gas farm trucks, combines is that some are a lot dirtier inside than other's.
Why Schaeffers #131? It is fantastic at removing varnish and lacquer from an engine. Stiction in the HEUI is due to varnish/lacquer build up over time 90% of the time. I have used the product over 20 years now.
Bob the origanal founder of "Bob is the oil guy" went as high as 4X the recomended amount in his daily driver and did UOA and took pictures for the sight and both were just fine. Normal UOA and varnish removed from cylinder head. In 20 year of using it I have never seen a bad UOA from it.
I am not a Veteran but my Dad is and oldest son is. I served my country another way but not one of the branches of the military. I understand how tight money can be and diffacult the VA and SSS can be deal with when you body is breaking done but not your spirit! I understand broken promises very well. The cheapest place to purchase a gallon of Schaeffer's 131 is on Ebay. You can sometimes find the gallons on Amazon but often they want to sell you a 4 gallon case. They do also sell a 12oz bottle on Amazon.
Schaeffer's 131 is a synthetic man made ester even though they do not tell you that. Molacule has at least one post on it on this sight. My Dad has a Ram 3500 with Cummins and I have had him use it as well even though he does not have HEUI and stiction. His has EGR and DPF and it is almost mandatory in my book to do this once a year 500 miles before oil change! It can also be used in the fuel to keep things clean on that side as well!
Thanks for the info
- Joined
- Jul 10, 2025
- Messages
- 195
I want to make sure I'm looking at the right stuff.
When I search Schaeffer's 131, I find a fuel stabilizer. Is this the stuff you are talking about? Using this fuel stabilizer in the oil as well as the fuel?
MolaKule
Staff member
Thanks for the link. It confirms the usage in the oil as Jack described.
CleanSump
Site Donor 2026
I wonder what HPL Dave would say about using one of their products.
- Joined
- Apr 23, 2026
- Messages
- 3
Power Service I just learned also has a newer product in a gold bottle that is a more concentrated fuel system cleaner than the grey bottle, which Walmart allegedly started carrying or will be soon. That might be worth a shot.
Hopefully the pickup foot on the bottom of the tank sending unit hasn’t broken off. It happens on all of them eventually and causes real trouble when the tank falls below 1/4, and it’s kind of a pita to fix.
Hopefully the pickup foot on the bottom of the tank sending unit hasn’t broken off. It happens on all of them eventually and causes real trouble when the tank falls below 1/4, and it’s kind of a pita to fix.
I was confused on that usage of 131 as well. I'd still be leery of it though.
There are more proven treatments and options. Again, stiction is less common on the 7.3 than the 6.0L and there are a lot of other items to check off the list first when it comes to hard cold starts. Also the HEUI engines can test for that. A buzz test will audibly tell you if the solenoid is moving and how well. IF you have a issue that is found by the buzz test and have thoroughly maintained the engine, that's when to determine if an additive will work or mechanical repair.
There are more proven treatments and options. Again, stiction is less common on the 7.3 than the 6.0L and there are a lot of other items to check off the list first when it comes to hard cold starts. Also the HEUI engines can test for that. A buzz test will audibly tell you if the solenoid is moving and how well. IF you have a issue that is found by the buzz test and have thoroughly maintained the engine, that's when to determine if an additive will work or mechanical repair.
I would suggest "Howe's Diesel Treat" in the fuel every time you fuel up. I used it for years in my big trucks. I purchased through my local distributor by the case to get a really good price. Double dose on the first 2-3 tankfulls then back off to the regular dose. You can't over-dose with this stuff. I am guessing you will have good results, I did.
https://howesproducts.com/products/diesel-treat?
Similar threads
- Locked
- Locked
- Locked