M20TN_Driver Posted May 6, 2023 Author Report Share Posted May 6, 2023 I've heard a million different things on MMO. I've heard some very positive and then I have heard basically neutral. I've never heard anything negative about the use of MMO. Apparently, this stuff has been around for 60+ years and people are still recommending it. I think that is meaningful. The ratio, according to the application is no more than 25% of your total should be MMO. So in a four-quart engine, you could add an entire quart. I run at 6 qts and add a single quart. Usually only at the initial oil change and then I just add 4-5 qts over the course of the next 25 hours of flying. I added this because my engine got to the point of burning 1 qt per hour. Now I am burning 1 qt every 4-5 hours. You can draw from that what you will, but it seemed to have made an improvement. My compressions are all in the 70's and generally, the engine flies very well save the oil burn. The ring flush is what Saavy recommended I do--as the thought is that the oil scavenge rings are likely clogged with crud that the flush should help with. This is a pretty nasty mixture of solvents...so much so that you have to remove your quick drain for fear of softening the o-rings. Regardless, old engines seem to need a bit more attention. I fly ~100hrs per year so. the engine sees a good amount of use. Quote Link to comment Share on other sites More sharing options...
Fly Boomer Posted May 6, 2023 Report Share Posted May 6, 2023 17 hours ago, LANCECASPER said: With the starter adapter slip-issues on Continentals I wouldn't run anything but engine oil in your engine. And under no circumstances would I replace a quart of approved oil for MMO. I've heard of people running up the engine with a little MMO as a flush just before an oil change, but in no way does that have the viscosity to protect for wear if you run it continually at high power settings. Got any opinions on Phillips XC 20W50 vs AeroShell W100? I have a few gallons of Phillips on the shelf, but my airplane (TSIO-520) had been fed AeroShell for a few years before I bought it. I also have CamGuard on the shelf, but not planning to use it. Quote Link to comment Share on other sites More sharing options...
LANCECASPER Posted May 6, 2023 Report Share Posted May 6, 2023 3 hours ago, Fly Boomer said: Got any opinions on Phillips XC 20W50 vs AeroShell W100? I have a few gallons of Phillips on the shelf, but my airplane (TSIO-520) had been fed AeroShell for a few years before I bought it. I also have CamGuard on the shelf, but not planning to use it. I use Philips XC 20W50 1 Quote Link to comment Share on other sites More sharing options...
LANCECASPER Posted May 7, 2023 Report Share Posted May 7, 2023 6 hours ago, M20TN_Driver said: I've heard a million different things on MMO. I've heard some very positive and then I have heard basically neutral. I've never heard anything negative about the use of MMO. Apparently, this stuff has been around for 60+ years and people are still recommending it. I think that is meaningful. The ratio, according to the application is no more than 25% of your total should be MMO. So in a four-quart engine, you could add an entire quart. I run at 6 qts and add a single quart. Usually only at the initial oil change and then I just add 4-5 qts over the course of the next 25 hours of flying. I added this because my engine got to the point of burning 1 qt per hour. Now I am burning 1 qt every 4-5 hours. You can draw from that what you will, but it seemed to have made an improvement. My compressions are all in the 70's and generally, the engine flies very well save the oil burn. The ring flush is what Saavy recommended I do--as the thought is that the oil scavenge rings are likely clogged with crud that the flush should help with. This is a pretty nasty mixture of solvents...so much so that you have to remove your quick drain for fear of softening the o-rings. Regardless, old engines seem to need a bit more attention. I fly ~100hrs per year so. the engine sees a good amount of use. That 25% recommendation is for automotive engines (https://marvelmysteryoil.com/blogs/how-to-use/automobile). Nothing on their website says anything about it being approved or recommended for certified or experimental aircraft engines. I do doubt that the car manufacturer would honor the warranty if it was used in their engines. A ring flush with MMO is done without running the engine and is in there a short period of time. If those MMO solvents soften the o-rings on the quick drain during a ring flush, what is it doing to seals and gaskets if you use 25% of it with your oil all the time? Write an e-mail to Mike Busch and see if he recommends using it for 25% of your oil capacity. Quote Link to comment Share on other sites More sharing options...
mike_elliott Posted May 7, 2023 Report Share Posted May 7, 2023 On 11/29/2022 at 8:01 AM, GeeBee said: I had an O-320B2 done at Gann. Purred like a kitten, on the dyno turned 173hp even though rated at 160. I sold the airplane and the new owners report it is strong. I also had a friend with a Baron that had both engines done at Gann. They are running really good. Carlus Gann does excellent work. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted May 7, 2023 Report Share Posted May 7, 2023 I use MMO (10%) for my pre oil change flight, it has the viscosity of water so thins the oil. I only use it for a short flight and then it’s replaced with fresh oil. 1 Quote Link to comment Share on other sites More sharing options...
EricJ Posted May 7, 2023 Report Share Posted May 7, 2023 O-300 operators tend to use MMO in their oil routinely, but it works well for them for whatever reason. A friend uses it regularly in his Cherokee, but he puts in the fuel, which is also pretty common to do. It's helped his engine operations, and there seems to be reasons for people to do that. People have been putting MMO in the oil and fuel tanks of airplanes for many decades, and I think if it were an issue to do so we'd know about it by now. I don't think it's the best thing to do if you don't have a specific reason to do so, but for the things that it's typically used for there's a large body of history indicating that it's not going to cause huge issues if done properly. Quote Link to comment Share on other sites More sharing options...
GeeBee Posted May 7, 2023 Report Share Posted May 7, 2023 MMO was originally designed to be a valve lubricant, not a bearing lubricant. In fact in the "old days" they, MMO, even sold an injector unit that used breather pressure to push it into the rocker cover space. A lot of engines in those days had splash rather than pressure lubrication and it was often difficult to get good lubrication to the upper valve train. It was designed to be burned off in the combustion process (which created its own problems). I would not be running it across crank and connecting rod journals. 1 Quote Link to comment Share on other sites More sharing options...
RoundTwo Posted May 7, 2023 Report Share Posted May 7, 2023 I don’t think the jury will ever come up with a verdict on MMO. Some people believe in it and some people don’t. However, I don’t think anyone says it’s bad; just question whether or not it really does anything. I used to mix it with my gas in my Cherokee and also ran it in my motorcycle. Never had a problem, or any evidence it did anything good either. I grew up around it, running it in almost everything, so that stuck with me. I guess it’s kind of like being Greek and using Windex. Quote Link to comment Share on other sites More sharing options...
EricJ Posted May 7, 2023 Report Share Posted May 7, 2023 In the automotive world when rehabbing an engine that is old or has sat for a long time or has been neglected, it's not unusual to run some good Automatic Transmission Fluid in the oil for a while. It works really well to de-sludge stuff and clean out the internals without having to open up anything. ATF has a lot of detergents and other stuff that helps to do this, and it doesn't seem to hurt anything. I think MMO does a similar thing in that it helps keep things cleaner inside than the oil alone will do, particularly regarding deposits that may stick valves or rings. For engines that may have slightly more restrictive passages or narrow galleries or spots where crud collects or just a larger pressure drop across the distribution system, running something like MMO may have noticeable benefit. The O-300 seems to be a notable example given the number of operators who use it and claim improvement. Word is it was recommended by Aeronca in certain engines, and was commonly used in radials back in the day. Lots of the old guys swore by it. Given the long history of the stuff, if it caused problems I suspect we'd know by now. 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 7, 2023 Report Share Posted May 7, 2023 Some people put it in the gas… Some in the oil… but none for the electric vehicles yet… Mr. Marvel was known for his carburetor… https://www.topspeed.com/every-reason-you-should-use-marvel-mystery-oil/#the-history-of-marvel-mystery-oil Nobody mentioned if MMO dissolves fuel tank sealant…. Use caution on this one… One person put gas in the oil sump to help wash out the sump… lots of sludge just sits there, and doesn’t move… Regarding oil leaks that make a mess of the rings… Is that an oil control ring that has been worn or is wearing…..? Does changing out the oil control ring help with that situation? How much effort does it take to swap an oil ring? It is nice to have a modern plane where the manuals are 100s of pages long… most fuels and additives have been tested and documented and covered in the documents… including the POH. Oddly, I haven’t seen the MMO show up in the documents… maybe it is in the standard Mechanic’s maintenance procedures…? If it is any good…somebody has documented it somewhere… an easy project for a budding engineer to write a Master’s thesis about. PP questions only, not a mechanic… best regards, -a- Quote Link to comment Share on other sites More sharing options...
Fly Boomer Posted May 7, 2023 Report Share Posted May 7, 2023 35 minutes ago, carusoam said: Mr. Marvel was known for his carburetor… https://www.topspeed.com/every-reason-you-should-use-marvel-mystery-oil/#the-history-of-marvel-mystery-oil Was that article written by ChatGPT? Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 8, 2023 Report Share Posted May 8, 2023 1 hour ago, Fly Boomer said: Was that article written by ChatGPT? From their website… TopSpeed team consists of writers from diverse backgrounds in all facets of the entertainment industry brought together by a passion for all things entertainment and a goal of providing the best, as well as most engaging, content possible for visitors to our site. They didn’t specifically say it wasn’t written by a chat bot… I always think entertainment and engine maintenance go together… Best regards, -a- Quote Link to comment Share on other sites More sharing options...
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