DCW Posted October 8, 2022 Share Posted October 8, 2022 Hi All. I think that this is one for Jon. I recently purchased the new (red) laser fuel from Model Technics, (Optimix), not the low oil variant and used it for the first time today (08/10/22). I decided to check the fuel out on my trusty old OS 48. After the first flight the underside of the aircraft was coated in oil with black streaks evident. Also dripping out of the silencer was very black blobs of oil. When using the old purple fuel this never happened, in fact after 26 flights, about seven hours flying time with this engine, (OS 48), I never even needed to clean the underside of the aircraft and the inside of the cowl was always dry. I used the old purple fuel, (15% oil) in all engines not just Lasers and the engines never ran so well, never overheated and most of the time I didn't even need to use an electric starter. I will not be using this fuel again until after Jon's advice. Many thanks David Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted October 8, 2022 Share Posted October 8, 2022 Loose silencer parts Form black sludgy oil to emit Tighten up the bolts Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted October 8, 2022 Share Posted October 8, 2022 Tried to edit but too late Any aluminium surfaces rubbing in contact with oil makes this black sludge. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 8, 2022 Share Posted October 8, 2022 Send it to me David, the more oilier the better,,,🥳 Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 8, 2022 Share Posted October 8, 2022 Hi David Did you re tune the engine much after changing fuel? I ask as the new fuel does demand a retune on both needles to get the engine running cleanly. In all of the engines i have switched to it i have needed to lean the needles, slow run in particular. As the FS 48 uses an air bleed carb the adjustment will be reversed so opening the screw leans vs a twin needle carb where 'tightening' leans. This might explain the oily mess. Denis's comments about the black streaks are perfectly valid. If most of the oil is red/dirty red brown colour with only a few streaks then it is likely to be as he suggests. I use this fuel in my enya 53 and OS FS40 and both really like it. I have also run an OS52 i am repairing on it, but this has only been bench run so far before ending up in a flair pup (i hope). I will ultimately transition all of my non laser engines to it but i am all over the place with fuels at the moment as my fleet are configured for 5 different fuels at the moment! The joys of testing things i guess. IN the end i will settle on the 15% and 7% laser fuels, i just need to burn through the stocks of older fuel i have on the models that still use it. Quote Link to comment Share on other sites More sharing options...
DCW Posted October 8, 2022 Author Share Posted October 8, 2022 Thanks Jon, thanks everyone. I will tighten my nuts and reset the engine. Apart from the oily mess the engine ran very well and tickover was as before, very slow. Happy landings David Quote Link to comment Share on other sites More sharing options...
DCW Posted October 12, 2022 Author Share Posted October 12, 2022 There’s no fuel like the old fuel! Sorry about the title, just couldn't resist it, not strictly true I know, but now it’s time to put things to the test. Experimenting with my now ancient OS48, I completed two ten minute flights with the old purple fuel and two flights with the new Optifuel, (branded Technics), variant. Both Laser fuel with 15% oil. The fuel tank was completely drained and filled up with the old purple fuel. Two flights were completed with the engine setting as before fully leaned out. After these two flights I removed the plug for inspection, no blackening was noted. Next turning the engine over I noted any dripping oil from the exhaust, this was almost clear. After fully emptying the tank it was filled with Optifuel Laser fuel, the carburettor airblead screw was leaned slightly, about one quarter turn anti-clockwise. Starting the engine the main needle valve was fully leaned out for maximum rpm. This was about 30-40 degrees more than with the old fuel. Two flights were completed and an inspection was carried out. The plug was blackened around the base but the element was perfectly clear. As before residue emanating from the exhaust was notably black. The old purple fuel is no longer available and if any retailer had some it would probably be old stock. Therefore there being no other choice I will persevere with the new stuff and next try it in a Laser 70. Happy landings David Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 12, 2022 Share Posted October 12, 2022 I flew with my laser 70 ( or there about ) with french 'Technofuel' complaints about smelly castor oil 🥳, leaned it out nearly a 1/4 of a turn on the main needle nothing else, 3 eventless flights,,,as also did my Mirage with it's Piped Novarossi. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted October 12, 2022 Share Posted October 12, 2022 22 minutes ago, DCW said: As before residue emanating from the exhaust was notably black. The only notable origin for black oil residue is from metal moving parts usually aluminium. Something inside the silencer, usually the baffle, or sometimes the cone in some silencers, is moving and rubbing creating the mess. A part should fall off eventually due to this vibration and wear, and the oil will run clear. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 12, 2022 Share Posted October 12, 2022 I wouldn't worry about the black, it doesn't matter what fuel my Rossi .40's run on it's always throwing out black. Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 12, 2022 Share Posted October 12, 2022 1 hour ago, DCW said: There’s no fuel like the old fuel! Sorry about the title, just couldn't resist it, not strictly true I know, but now it’s time to put things to the test. Experimenting with my now ancient OS48, I completed two ten minute flights with the old purple fuel and two flights with the new Optifuel, (branded Technics), variant. Both Laser fuel with 15% oil. The fuel tank was completely drained and filled up with the old purple fuel. Two flights were completed with the engine setting as before fully leaned out. After these two flights I removed the plug for inspection, no blackening was noted. Next turning the engine over I noted any dripping oil from the exhaust, this was almost clear. After fully emptying the tank it was filled with Optifuel Laser fuel, the carburettor airblead screw was leaned slightly, about one quarter turn anti-clockwise. Starting the engine the main needle valve was fully leaned out for maximum rpm. This was about 30-40 degrees more than with the old fuel. Two flights were completed and an inspection was carried out. The plug was blackened around the base but the element was perfectly clear. As before residue emanating from the exhaust was notably black. The old purple fuel is no longer available and if any retailer had some it would probably be old stock. Therefore there being no other choice I will persevere with the new stuff and next try it in a Laser 70. Happy landings David Got any photos? Im curious to see what you mean exactly by 'black'. Are we talking chalkboard, piano, bbq sausage? Im not trying to be difficult just understand what you are seeing as i have not replicated it on any of my own engines. Black with a metallic sheen is the classic aluminium powder and oil combo, but the red dye in the fuel can also turn a funny colour when heated. This is often a very dark brown but could fade to black. The 360v in my sea fury has always emitted dark oil from the breather pipe as it works hard and i do not spare the horses. Inspections have shown no problems with it though Petrol engines usually emit black goo as well and many of their oils start off red in colour so it might just be the dye. Another possibility is the new oil is having some sort of detergent effect on built up carbon within the engine and is flushing it out. Even synthetic oils burn off eventually and ML70 does burn to a brown or black stain over time. Its not going to coke up the engine like castor, but it may stain it. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted October 12, 2022 Share Posted October 12, 2022 1 hour ago, Paul De Tourtoulon said: I flew with my laser 70 ( or there about ) with french 'Technofuel' complaints about smelly castor oil 🥳, leaned it out nearly a 1/4 of a turn o Really? Whatever anybody thinks about it’s drawbacks versus synthetic oil, the aroma (I couldn’t possibly refer to it as a smell) has never raised a complaint in any comments I’ve read. My personal dislike is the soapy smell given off by the old Laser fuel - but opinions on this may vary! 1 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 12, 2022 Share Posted October 12, 2022 More of a bad joke, I turn up on the field with a different plane most days, fire up and fly, but for once I had to tune it up and they were all seated in my line of fire 😆 Quote Link to comment Share on other sites More sharing options...
John Wagg Posted October 12, 2022 Share Posted October 12, 2022 (edited) Sorry to be sort of off-post but can anyone tell me what this fuel is ? To my eyes it is green and it is supposed to be 5% Laser. Cheers What ever it is I'm not impressed. It is not like the 5% Laser I had previously. I know things have changed but I'm a bit confused. Edited October 12, 2022 by John Wagg Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 13, 2022 Share Posted October 13, 2022 Did you buy it new John or 2nd hand? Either way there are only a few options: Its some dish soap someone put in a laser5 bottle Its the old 'purple' model technics made fuel but something really strange has happened to it Its the optifuel manufactured 'purple' fuel but its green as their dyes were done differently. Incidentally, whats up with it? Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted October 13, 2022 Share Posted October 13, 2022 The light purple coloured fuels had a tendency to change colour to a dirty green/grey , as above if exposed to sunlight. Fuel still OK but looked horrible. If in doubt dump it and get some fresh . It's cheaper than buying a new engine ..... if you can find one . Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 13, 2022 Share Posted October 13, 2022 (edited) 17 minutes ago, Engine Doctor said: The light purple coloured fuels had a tendency to change colour to a dirty green/grey , as above if exposed to sunlight. Fuel still OK but looked horrible. If in doubt dump it and get some fresh . It's cheaper than buying a new engine ..... if you can find one . I found ML70 oiled fuels went sort of brown when old 😕 The thing that strikes me about the fuel in the photo is its opacity. It looks like green milk rather than a green clear liquid like methanol. Could some water have got into it? Edited October 13, 2022 by Jon - Laser Engines Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted October 13, 2022 Share Posted October 13, 2022 Hard to tell Jon as the plastic bottle is opaque and fuel may be clear . If fuel is opaque then in my mind its contaminated and should be dumped . John. Is it possible to show fuel in a clear glass container ? 1 Quote Link to comment Share on other sites More sharing options...
John Wagg Posted October 13, 2022 Share Posted October 13, 2022 (edited) Appreciate the replies and thanks. I bought this from Leeds Model Shop 8/3/22 this year. Model Technics Laser 05 5L Nitro Glow Fuel MTLS5 It doesn't seem to develop full power and I have difficulty in getting a reliable idle. This is on an engine (SC30FS) that ran very well on both Optifuel 5% and original Laser 5. Yes it starts and runs but doesn't feel right. Not done any real tests to compare. I've not done much flying this year generally because of the weather so it's lasting a long time. I suppose I should have queried it at the time but with the changes that Laser 5 etc were going through I just assumed it was OK. Especially when people were saying that the new Laser fuel required the settings tweaking also helped settle suspicions. It's only recently when forum members mentioned purple and red colouring that started me wondering why is mine is green.🤢 Actually looks worse in a clear jar than in the plastic container. Edit - By the way the exhaust residue is clear. Very sorry for the post diversion. Edited October 13, 2022 by John Wagg Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted October 13, 2022 Share Posted October 13, 2022 (edited) Have never seen fuel that colour or cloudy ? Even heavily water contaminated fuel will sart readily but also stops without warning. I wouldn't be happy with that and would dump it . I'd also have a word with the supplier or shop where I bought it and see if there were any other complaints or similar events. Its possible it was a one off contaminated container. Edited October 13, 2022 by Engine Doctor Quote Link to comment Share on other sites More sharing options...
Don Fry Posted October 13, 2022 Share Posted October 13, 2022 Can algae grow in water contaminated fuel? Colour is right. Quote Link to comment Share on other sites More sharing options...
Jon H Posted October 13, 2022 Share Posted October 13, 2022 Shame its not paint. Its about the right colour for a Spitfire... Anyway, it looks wrong to me and agree with ED As that fuel (ml70 technics by opti) is now dead if this is the last you have then i would use it for weedkiller on the path or keep it for washing engines/parts in the future. I would also let optifuel know directly with the photos just to ask what/why has this happened, have they seen it before, etc. Its helpful for them as if you report it, and then someone else does, and someone else they can see a pattern and perhaps take action. If its just yours then it can be dismissed as a one off. I wouldnt troble MSL with it as they just send the boxes out and cant be faulted at their end. Don, you can get all sorts of things growing in fuels. Kerosene for full size aviation can grow things in it and you really dont want to see what can end up growing in the soluble coolant oil we use in the machines here. It would make you heave i can assure you. If memory serves you could get growth in castor based fuels, and in my experience the sical additive MT used to use must have some sort of organic component to it as i have had it go rancid on me in the past, especially if left in the sun. My current bottle of old laser 5 is starting to pong but it seems to run ok. The worst was an empty bottle of fuel i had which i left in the sun for a while. I wanted to mix up some screen wash for my car and so thought this container was perfect. The stink from opening that bottle was quite something. So i washed it out, mixed up my screen wash, didnt use it all and I got all sorts of weird stuff growing in there and the washer fluid stinks after a few days. Worse still, the washer bottle in my car is contaminated with whatever bug was in the fuel bottle so my washer fluid goes rancid after 2 or 3 days. Who knew washer fluid was such a great culture? At some point i will just fill the blasted thing with dettol/bleach or something to purge the system but i was always worried about busting the seals or pipes. I have been living with it for the past few years but i need to fix it. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted October 13, 2022 Share Posted October 13, 2022 Try some copper sulphate solution. Poisonous as hell, easy on seals. Might even clean the windscreen. 1 Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted October 13, 2022 Share Posted October 13, 2022 (edited) Well adding a twist to the discussion, BNIB and I broke the seal + its been stored in a cool dry place out of sunlight from LMS. Not tried it yet as I am still using up far older stuff, but I'll get to it at some point. Out of interest I'll take the now opened gallon and do some back to back testing with the old stuff on a model I can get to both needles easily. Comments? Edited October 13, 2022 by Chris Walby 1 Quote Link to comment Share on other sites More sharing options...
Phil Olson - Model Technics Posted October 21, 2022 Share Posted October 21, 2022 If its got a 5ltr label on it, it will be the Klotz oil variant by Optifuel as Model Technics only sold UK gallons in the UK ! Quote Link to comment Share on other sites More sharing options...
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