Hello,

A certified engine mechanic told during a seminar (here in Italy) that's a common practice to add a slight quantity of oil (really slight: something like 2,5cc for 10 Liters) to the gasoline in order to improve the engine life (especially if it's not used every day) in high humidity and low temperature environment.

An example of oil to use could be Castrol TTS 2T (btw, of course we're speaking anyway of 4 stroke engines)

Does anybody ever heard of this practice?

Thanks!

We have used Marvel Mystery Oil in our 100LL tank for as long as I can remember. 1 gallon MMO/300gal Avgas. If my math is correct I think that's about 33 1/4cc per 10 liters. You may want to recheck that. I was told it helps remove carbon deposits & helps the valve guides. The meter on one of the pumps that's used most is over 19,000 gallons & none of us have had any engine problems with it. I'm not sure how that Castrol Product would compare, but I know of other guys using MMO in fuel.

You can also add a pint of it a few hours before an oil change & it will remove carbon & oil sludge from the engine internals.

Marvell Mystery Oil, 4oz/10 gal of gasoline in the tank when filling....upper cylinder lube and helps keep the plugs from lead fouling..have used it for years....and it works, especially to keep the lead fouling down on a Continental Engine.

I've added oil to the fuel on my tractors and skidsteers but not my planes. It definitely helped the old 8N and the Wisconsin engined (aircooled) Bobcat skidsteer.
I have done as others though and put in the occasional MMO to my planes fuel when I have used Mogas.
WW

Marvel Mystery Oil has been a favorite for decades, but more recent testing has shown no benefit.

I use a product called ASL Camguard, and it DOES have extensive testing to suggest that it prevents premature corrosion in engines that dont run regularly or frequently. In fact, right now, that is the only OIL additive that is approved by Lycoming for their engines. Camguard goes in the OIL, not the fuel.

Don't waste your money on MMO or other fuel additives (unless you're running one of those Lyc engines that Lyc recommends a specific fuel additive). Buy some Camguard, and do your engine a favor.

MTV

Marvel Mystery Oil has been a favorite for decades, but more recent testing has shown no benefit.

I use a product called ASL Camguard, and it DOES have extensive testing to suggest that it prevents premature corrosion in engines that dont run regularly or frequently. In fact, right now, that is the only OIL additive that is approved by Lycoming for their engines. Camguard goes in the OIL, not the fuel.

Don't waste your money on MMO or other fuel additives (unless you're running one of those Lyc engines that Lyc recommends a specific fuel additive). Buy some Camguard, and do your engine a favor.

MTV

MTV-

How often are you putting the Camguard in? I fly about every day for at least 2 hours or so. I was told to use it every couple weeks. Curious what you think. Are you putting it in every time you get gas? I am thinking not, but curious???

Thanks

AKT

mtv wrote:Marvel Mystery Oil has been a favorite for decades, but more recent testing has shown no benefit.

I use a product called ASL Camguard, and it DOES have extensive testing to suggest that it prevents premature corrosion in engines that dont run regularly or frequently.
MTV

Interesting, do you have a reference for either of these test results? I'd like to read up on it, I actually just pulled a cylinder off yesterday to fix the exhaust studs & the camshaft was in great shape & no corrosion.

Apples and oranges here??
MaxB was talking oil in the fuel and that what most use MMO in
CamGuard is an Oil additive you put in the crank case.
I use'm both, MMO sure doen't hurt in the fuel!
I put MMO in the oil in the round motors just because an old boy who flew 1000's of hours with round motors told me to!! 1 Quart in with the new oil at oil change.
MHO & $.02
GT

When I started flying Beavers in 1980 or so, our old time Chief of Maintenance told me to religiously put MMO in the OIL and a dab in the fuel. I did so. Now, the same fellow, who was very knowledgeable also said to NEVER put anything but mineral oil in the radial engines. Well, I think nearly everyone has figured out that AD oils work just as well in radials as they do in horizontally opposed engines by now. And, the same goes for adding a dab of MMO in the fuel.

ASL CamGuard is an OIL additive, NOT a fuel additive. My recommendations came from Lycoming. Lycoming has now stated in writing that ASL CamGuard is an approved additive for Lycoming engines. In fact, it is the only additive approved by Lycoming, with the exception of the fuel additive that they recommend for those unfortunate enough to still be operating one of those bastard O-320s that had valve problems.

Do a little poking around on Lycoming's web site. Lots of good information there.

MTV

FWIW I'm a believer in using MMO in the gasoline.The one time I did not use it (on the strong advice of the seller's mechanic), the T-craft stuck an exhaust valve in Childress Texas and I had to wait a day for another mechanic to come and do the "rope trick" to clean out the valve guide.

I've related the following story before but it is relevant to this thread so I'll repeat it here in brief...

When I asked this old mechanic about the use of MMO (and STP also) to keep an engine healthy in the high Texas heat, he said that a chemical analysis would likely find MMO and STP in a lot of the engines there. When I asked him what the Administrator would have to say about it, he looked over his glasses and said "Son, the Administrator is not from Texas."

So my personal viewpoint is safety first. And while we're on the subject of safe operation of old-tyme low-tech airplane engines... the Administrator is not from California either

And, the Administrator doesn't BUILD "old tyme" engines, but Lycoming does. Their approval or disapproval of additives has nothing to do with the FAA. It has to do with their experience in building and overhauling thousands of engines.

MTV

OK, looks like that the mechanic which told me about oil was right

Thanks to all for the ideas and contribution, I've just learned a lot! (and that's just the beginning!)

Max

asl camguard in the oil at recommended rate at every oil change and 1oz. of penzoil 2 cycle synthetic oil(high flash point) per 2 gallons gas. So far no stuck valves and havent seen the inside of the engine yet and im hoping not for 1500-2000 hours. time will tell.

To each their own of course. For me, MMO works. Although I am definitely NOT an accredited engine expert, I do know that on the old Continental A and C engines there are areas that are not well enough lubricated by splash and drip oil. MMO in the gas puts a little extra penetrating, lubricating, cooling, and corrosion resistant oil in the valve system, particularly the valve stems and guides. The film of oil makes the valves and rings seal better to some degree. Loosening up the gunk behind the rings is a help too.

Other than oil building up a little faster on the plugs, and needing a little more frequent plug cleaning, I cannot see any downside to a little thin oil in the fuel and I can certainly see the upside.

No idea if MMO helps in the oil or not.