It may be a simple question, but it's not a simple answer. The oil question has been beaten to DEATH on this forum. A number of times. Oil is like religion, or politics. If you have an oil you like and are getting good results with, stick with it. Opinions will differ as to what is OK or not, and I am staying out of this discussion just like Pat and the others.

Part of the reason no one will answer you is it will start another long winded thread that ends with no value. Another part is that people come on here and ask the SAME questions, again and again without checking to see if perhaps it was covered in the past. There is a search function, get to know it well. I bet 75-80% of the questions that get posted in the next week have already been comprehensively discussed and covered in the past year. No need to reinvent the wheel or rehash old topics.

Mark

Thanks mmattockx. I honestly didnt know what to think with some of these replys. I understand fully what they meant know and were it would go. I thought it was something specific regarding the oil itself.

I do have my favorite oil choices as well and like most I probably will go with the manufactures recommendations with a little more added for safety.Thanks again.................

OK Crash I checked post #3 and I was replying to DR1 in post#2 who stated he's been using Saber for several years, so I replied the quote above

Sal,

There are only a few engine companies that actually stress test an engine and it's oil. Fewer still that test just the oil, and generally only long enough to see that the oil meets minimum standards for the duration of the testing period. DL is not any of those, nor was BME, Taurus, or Brison. DA, Herbrandson, and 3W get their engines tested indirectly via uav companies using the products in various enviornments over very long periods of time in extremely diverse conditions. I don't have a clue what goes on behind the doors with ZDZ or MVVS. I doubt (but don't actually know) that Chinese engine manufacturers have any type of ongoing oil analysis programs that cover their products.

Those that seriously test engine oils under high stress conditions will not use Amsoil products. There's a reason they have never been approved for certificated full scale air cooled aircraft engines and stress testing with our smaller air cooled engines has noted similar results. The stuff seems to work ok for light duty use or where cooling is not an issue but when the engines start running hot or at peak, or lean of peak cht levels, look out.

So that's the answer as far as I'm in the mood to go with it. Buy what you want and mix the stuff just as thin as you think you can get away with. Personally I won't go leaner than 70 or 80-1 with any oil I use and some of them are manufacturer spec'ed to be usable at 100-1.

On a side note, I was looking at an engine that has been using Opti-1 at their ratio of roughly 114-1. The pistons, rings, and cylinders are now junk in that engine, especially after one cylinder "grenaded". Before the cylinder parted company with the engine there was a lot of evidence that the oil was not doing the required job. There were other contributing factors, but the oil and it's lean ratio didn't help any.

OK folks, the door's been opened and I have a few nomex flight suits so I can live with the heat that's about to commence. Pardon me if I don't reply.

But Pat, the amsoil is formulated to run at 100:1. It's more slippery than other brands of oil and formulated to run that lean. Besides, what's a little piston scuffing going to hurt compared to a little extra time of wiping down the plane?

Hi,

As previously stated, this topic has been completely hashed out. Since I stress engines with my work pulling heavy loads and generate heat, my oil mix tends to be 20:1 pensoil on the heavy pullers and 40;1 pennzoil on the medium working engines. Even at 20:1, I cooked a cylinder on a 3w-200 this past summer. The mixture was good but the engine load was apparently too much. Next summer, we will test different props and try to increase airspeed and cooling. Under my regime, thin oil mixes fail quickly. Under most very light RC hobby flying loads, engines can tolerate limited oil amounts like Amsoil saber at 100:1. People need to choose the oil mix and brand they feel comfortable with and do their own testing.

Elson

Thanks for the insight and help Pat. I dont really visit the engine forums to much as I do the aerobatic and 3D spots. So I am a little behind with the latest info. I Probably will stick with the Amsoil but at 75-80 to 1 and retune. Mainly for warranty issues.

Elson,

Do you do any baffling or other airflow management to help with your cooling issues? I know I have seen your pics before but all I remember seeing is shots of uncowled engines.


Mark

Mark,

The engines are exposed but we have ducting around the cylinders to direct airflow around the cylinders including the back of the cylinder. One plane with a 212 4 cylinder worked fine and did not seem to get hot. A second plane with a 200 2 cylinder also worked great and did not seem to get hot. The third plane with a 200 2 cylinder flew for a number of flights, but then appeared to get hot after about 20 min of net pulling, stuck a ring, lost power and did a cool tail slide into the woods. Perhaps we developed a fuel flow problem which leaned the mixture or some other problem. The tail slide only destroyed the fuse with minor damage to tail and wings. The plane is ready to go for another season.

Elson

Pat,
It seems better I'll do my thinking when the day is done. For the time being, just gathering data. 300 hours without attendance is a lot. Thet makes me think of ship's diesel maintenance schedules again. These ran only at 90 - 130 rpm, so in your engines, there's a lot more combustion cycles involved.
I doubt if 3W ever tested an engine that long. I also doubt that there are model pilots having that number of hours on their engine before they discard it, or turn attention to a new project.

I will say this again....DA recommends other oils as well, Belray to name one, its in the manual but for some reason folks choose to ignore it.
My conversation with Brian when he was still at DA suggests that they have seen a number of failures with Amsoil but for other reasons still mention it.
They were more than happy with Belray and other GOOD quality oils run at the correct ratio.

Btw the only 2 DA100s I have seen cooked here were on Ams at 80-1

i am running the mobil 1 synthetic at 45:1 in my 3w 106 and zdz 160. no problems. i use pennzoil to breakin all my engines though.

Elson,

Thanks for the info. I figured you had worked on it, because you have done an excellent, thorough job of everything else. Any pics of the ducting? I am always interested in what others have done for cooling solutions, especially someone who runs their engines so hard for such long periods of time. PM me to send them off list if you want or if we are drifting too far OT here.

Mark

Excessive heat due to lack of cooling or improper needle setting is what seems to stick rings, at least that is what I have seen. Not the oil or ratio used as long as it is a quality oil. I still would never run any oil at 100:1, even Amsoil recommends richer mixtures. To this point I have never had an oil related failure and currently like the Pennzoil I am running at 32-40:1. Just took apart an engine and it was clean shinny with minor deposits that wiped away.

Isn't Mobil 1 synthetic auto oil?

I think he has mobil 1 2t which is a full synthetic 2stroke racing oil. I have the same stuff that I used in my Evolution 58. 7 Bucks at autozone for a Quart.

And not worth .02, IMO. I ran that Mobil 1- 2T. I could tell within a short time that the piston was going to glaze with a hard carbon, and the internals weren't very slippery. But it may have been me.... I have a couple quarts free for shipping...

Hi Sal98,

I'll try to respond. I think the previous replies are because of your assertion above. This has been endlessly discussed on these forums. Many very knowledgable folks with serious technical qualifications have posted. They have been shouted down by folks who often have only lightly formed opinions, not even experience. So...

Bottom line is that many folks have had lots of success with Amsoil Sabre at 100 to 1. Many have had success with all the oils you mentioned. Many have had troubles and failures too. Some of these failures could be traced to the oil used.

You should read and form your own opinions. I say this because facts are often buried by hype and marketing. Outspoken people often feel what they are doing is the best and will shout down all others. In the end you will be very happy mixing any of these fine oils as recommended.

My tips:
Cool the engine properly - don't assume a bit inlet = adequate cooling. Proper engine temp is life and power.
Mix your oil properly - always put oil in he gas (don't ask. Many have made this mistake).
Mix you chosen oil at oil manufacturers ratio. Where you are given a choice try to determine if your use is more or less severe. A properly cooled engine on a nice day does not work very hard.
Learn to set your needles. They move for a reason and there is a sweet spot. Learn to tune your engine. The manufacturer will only give you settings where the engine can be initially started. Pat Roy gave good advice above. Retune if you significantly change altitude. Retune if you change props. It won't take much but they do need adjustment.
Learn to read the plug color. I will often run a hard upline then kill the engine and dead stick in. This will give very good indication of mixture. It is not the ONLY way to do this. Pat's info above works well too. I just use this to sorta verify my setting.
Don't over prop. This loads the engine and creates heat. Find a suitable prop that keeps temps in control and gives you the performance you want.

Good luck. I like Belray MC1, Mobil 1, Pennsoil air cooled, 3W's oil and I'll bet I would be happy with many others.

Don't let the 3w oil sit for too long in the gas can. If you do shake vigerously before filling the tank.

Thanks solstice for all the help. I am very good at tuning and reading plugs, Learned the hard way with all the bad engines I always seem to aquire, but oil choice has always been by manufactures advice. Never new that people were haveing engine failures due to the brands of oil they used. I always assumed it was due to engines being run to lean or run to hard with the wrong props and wrong oil ratios. Know that I see the concern I will spend more time researching.

Those 100cc cylinders are much more dependant on combustion temperature control than smaller displacements. These 2" bores can detonate on pump gas if the mixture is too hot. I have induced detonation on a 30 and 40cc chainsaw engine with low octane fuel, they rattle for about 20 seconds and seize. Make sure your 200 twins are rich of peak power or use high octane fuel.

Hi Pat,

I didn't know that about 3W oil. Separating after sitting is not good. Frankly I've used all that oil up. It's expensive and not locally available so I don't use it any longer. I use Belray MC1 for everything, including my KTM300 motorcycle. Very fine oil that has given me no cause for concern. I realize my motorcycle experience does not translate, but I've burned about 1000 gals of gas with Belray MC1 in my 93 YZ250. I never had a failure of any kind. But of course this was water cooled.

In my models I have tried to learn from others. I played around a bit with the high ratio oils and got to clean out cruelly hard deposits all the while marveling at the lack of oil residue on my plane. Now I buy Belray MC1 at my motorcycle shop and have one oil for all my engines, very light carbon (if any at all), a little residue on my plane (running 40-1) and piece of mind. I regularly run a BME44, BME 102, DA50, Evolution 26gt2, Zenoah 26, and 3W80xi.

For me, Penzoil aircooled provided nearly the same results but was not available locally. So I don't use it. That's it, no better reason.

Thank you for all the information you've shared in these forums (RC Bugman too) and the heads up on 3W oil.

Now, if after this latest refresher course 101 on " What oils to use and how to mix them", if some folks still don't get it there is absolutely no hope for those hopefully unfortunate few.

Karol

Here I go against the grain again. I think too much of my engines to run a real lean gas/oil ratio. I like a margin of safety. I run Amsoil Dominator (50:1) at 40:1 with 91 octane gas in all of my engines and have for years. No over heating, no ring sticking, no excess carbon build up and great compression. There is a little black residue that wipes off easily with a paper towel. This residue is completely unlike glow fuel in that it wipes off without using a cleaner.

When I've had a cylinder off I find that the carbon is relatively soft and a little oily. When I've lightly scraped it I'll find a few places where the thin carbon will actually flake off revealing shiny metal below. Some other places, especially toward the exhaust require a little more scraping. I think some people are afraid that carbon will build up until the piston starts hitting the top of the cylinder. This just doesn't happen if the carbon is a little oily and soft. It sloughs off and goes out the exhaust. The ring or rings have always been oily and loose in the grooves. There has been no sign of piston scuffing. I truly believe more oil is better.

As Elson (RC Bugman) has so clearly pointed out that pulling draggy nets with RC airplanes is about the hardest environment for any RC engine. The oil that he uses can be critical for engine longevity. However, this is not normally the case for our gasoline powered engines. Proper air cooling is as or more important than the oil that we use. Oil also carries some of the heat off unless you are running a real lean mixture. Excess heat build up is a prime function in ring sticking. It gets really simple here: Almost any brand of 2 cycle oil will work fine if you don't mix it too thin, don't set your needle valves too lean and provide adequate cooling.

The question is, how many ways can you say the same thing?

Ken, we are trying to find that out.

Mark