I've seen posts about adding castor oil to fuel to raise the oil content. Is there a specific product (brand name) that people use for this?

I've got Morgan Omega Fuel and a Thunder Tiger Pro .46. Should the oil content be upped from 18% to 20% for this engine?

hey bubber,
ive been flying for 13 years and have never added anything to my glow fuel. i have only had one eng. failure and i had it under proped ( turning too many rpm's )
extra oil would not have helped in that case.
so i wouldnt worry about it.
this is just my OPINION. but ive never seen a need for extra oil
even during break ins on new engines.
southerngent

Sig sells castor oil by the quart. Your LHS should have it or can get it for you. Many engine reviewers suggest adding oil to bring the total to 20% or more. Dave Gierke has a column in the November 2001 issue of Model Airplane News--page 98+ about break-in and subsequent running. Regards, Al Sortwell.

I agree with Southergent, and have also never added oil to an engine. I personally feel that engines most often don't seize up because of lack of oil content, but rather because they have overheated because the fuel mixture was set too lean. Proper mixture allows more than sufficient oil to pass through the engine to give excellent wear characteristics and service. I've got engines with hundreds of flights on them still going strong.

Having said that, does it HURT to add more oil? Two stroke engines are probably more affected by higher oil content because since the oil doesn't burn, a higher oil content in the fuel means you've got to be closer to a proper mixture for reliable running, as it will load up a bit faster with a slightly richer mixture. At the same time, though, NOPE, you can't hurt the engine with too much oil. To me, it's kinda like using premium gasoline in your brand new car. You may FEEL better, but the engine doesn't care. Keep a proper fuel mixture, and your engine will LOVE you for it!

Tim

That's pretty much what I've learned... If the amount of junk that I have to clean up off of the outside of the plane after flying is any indication, it'd seem like there's plenty of oil in the mix ;)

DM

I really dont know, should I disagree with some of you or not on the subject of adding extra oil to the fuel or not, but here is my experience. I always add 2 oz. of SIG Castor oil to my fuel ( Ritches Brew), which has a 20 % oil content from the plant. I recently bought a Clarence Lee Custom K & B .61, in my opinion, one of the finest engines build. About 5 weeks ago, the engine seemed to have too much play in the wrist pin and crankjournal, so I send it back to Mr. Lee. He examined it, found that the bearings wore in excess of .002 - .006", and suspected not enough oil in the fuel, since I run all engines rather rich, he recommended adding another 2oz. of castor to the fuel to bring the total of oilcontent to about 24%. No problems now with the K & B, I may loose about 200- 400 rpm in performance, but look at the long shot. The more Lube you get to the internal moving parts , the longer it lives. We have some Fellows in the club who run Gassers, which are recommended for a 32 -1 mixture, but they run a 16-1 mix and do not suffer any performance problems, but may loose a plug once in a while. A small price to pay for a trade of the life of the engine.

Hey Buchtes, no problem on the disagreement, we don't need yes men, rather people to share their points of view.

AS long as you're having success with what you're doing, that's ok. Sometimes there are several ways to skin the same cat, right? If 24% oil works for you, great. My 2 strokes have had zero problems with 16% and that works for me.

Regarding gassers, I've been flying my first one this year, have over 100 flights and it's been basically "gas & fly". I still am using the 32 to 1 oil ratio mix. One reason I wouldn't go to a 16 to 1 mixture is because of the much increased carbon and varnish buildup. Fouling a plug is a small price to pay, but if the buildup sticks a piston ring (and it eventually will) the stuck rings WILL seriously score the cylinder walls. Since most modern gas engines use a super hard nikasil coating on the aluminum cylinder block rather than using a heavy cylinder sleeve, then the whole cylinder block is now trashed. At some point, I'll switch to an all synthetic oil, mainly because of the significantly reduced carbon and varnish buildup.

When you think about it, most gas engines we use have their roots in chain saws, etc. These engines are designed to run 12 hour shifts, 7 days per week, and they last for YEARS. They operate in a MUCH harsher environment than they'll see in our planes, with less cooling air flow, full throttle most of the time, being lugged down, etc. They'll see more running in a week than most gassers will see in an entire flying season. We might KILL our engines with lean mixtures, improper oil ratios, crashes, etc, but we DEFINITELY aren't going to wear these engines out.

If a little is good, more is not necessarily better.
Tim

Hello T-Mills. I'm not familiar with the newer nikasil cylinders, there kind of new to me. Back in the early 90"s I worked as a small engine mechanic and attended several schools for different brands, and all stressed the importance of a good mixture in the fuel. All recommended their own brand of oil for mixing, and all mentioned to use good, clean Gas from a clean container. I never encountered a engine that sized from a overly rich mixture, but seen bad pistons & cylinders because of too lean a mix or dirty gasoline. I dont think that as long as there oilfilm beetween the ring and ringgroove wall that carbon will set in, most of the excess oil will burn off in smoke. I've seen exhaust ports almost completely closed with carbon, but no carbon deposits on the ring or groove. Makes you think, does'nt it??

As you probably know, eliminating the cylinder sleeve offers the advantages of lighter weight, and better engine cooling, both important features that we consider when buying an engine. Matter of fact, one reason I bought my BME was that it was the lightest 100cc engine, being over 2 pounds lighter than the 3W-100 engine. This occurs at no wear penalty since the nikasil coating on the aluminum cylinder bore is super hard with excellent wear properties. Of course, this also means that the break in period is longer.

We both agree that lean running is a killer for sure! I wasn't thinking about carbon deposits sticking the rings since most carbon deposits occur where the flame front is, in the combustion chamber, and the ring lands are shielded from this. I was more thinking about the thicker varnish like deposits sticking the rings. My thought was that in these gasoline engines, the black fluffy carbon deposits caused by rich running isn't a large problem. Petroleum based oil, however, leaves a lot more residue when it's burned. The more oil you burn, the more residue there is, so I follow the manufacturer's directions to ensure sufficient oil for lubrication, but not so much as to increase residue. If he says 32 to 1 will offer the best balance between lubrication and deposits, then that's what I use.

Again, there's no set "right" way, whatever works is correct. I had a base gasket start leaking on my BME, and pulled the cylinder to replace it. All I saw on the cylinder bore were the hone marks......zero scoring, excellent wear pattern. Had normal combustion chamber residue, the engine was happy, so I'm also happy.

Like I said, at some point I'll switch to synthetic oil (following the manufacturer's recommendations for mixture) to get the benefit of greatly reduced deposits. The synthetic also has better wear resistance also, but, I'll never wear out an engine regardless of the oil I use, so that's a lesser point for me.

Fortunately, the lower operating temps of two stroke glow engines mean higher oil ratios don't significantly increase any tendency to deposit since the oil doesn't burn, rather just passes through the engine.

Tim

Model Airplane News just had an Article on this topic which read OK and the recommendations that were made were even pretty good. The article basically says that at extreme temps, caster "protects" better than synthetic. Kinda strange because if you were looking at automotive motor oil, synthetics are much better for most applications than dino oil, but that's another conversation entirely... I'd say if your glow fuel has at least 18% oil and some of it is caster, you're fine. If you're really worried about oil content, it's probably easier to buy fuel with extra caster in it. Sig Champion and S&W fuels have 20% oil content of which 50% of the oil (or 10% of the total) is caster and the rest is synthetic.

I have much esperience with 2 strokes, but not RC. The 2 strokes I know about are snowmobile jobbers. The 2 stroke snowmobile engines if they run with tooo little oil will run to hot (lean) and explode. HOWEVER I have heard engines blowing up due to the jetting being to small, for example, they use a 230 and the requirement is 250. This will cream a engine, I feel if your getting some extra fuel out of your engine (RC) you are getting propper lube, and its rich enough. Yesterday (wednesday) I broke my thunder tiger pro .46 in. Ran a tank through her, gunned her to full for about 20 seconds at a time. Towards the end I turned the needle so it was richer, well it ran much better. The engine afterwards was not even hot. What I mean is, burn you hot, it was perfect. I use 10% fuel in mine, not sure of the oil content, but ive used this 10% fuel in all of my engines, the .60, the .40 and this .46. I also don't push my engines, I don't run em full throttle from start to finish. I strongly reccomend some folks not run a engine full throttle for a long time. With a snowmobile 2 stroker, if its pinned for quite a while it will fail to due heat. I think while in flight, gun it during tricks and give it a few passes of 1/2 throttle (if your plane fly's well at half) and let her cool a little. This will help. Ya know what they need to make? A water cooling system for these engines, put some type of chemical that is cold, or stays cold. Runs through the engine, through a small air cooled type deal and back into the tank. I dunno just a idea :). Usually a engines heat, and what not will kill a engine before lube. But I dunno, im going with the 2 stroke basics, and keep in mind, some will blow up and some won't, depends if it was assembled right. But I think it also depends on how much fuel they are getting, to little, to hot, to much, well it will just gum up a little faster.


Jeff