freakingfast

My Feedback: (3)

I would appreciate some fuel Guru's opinions about oil for run-in and duty fuel for a K&B high out-put ducted fan engine (tight, ABC). These engines desire 23% oil and I've read somewhere to add 3oz. to 1gal. of turbine oil http://www.sacskyranch.com/cgi-bin/a...e_Oil_220.html to standard 15/15 Power Master to augment the oil package. My question is, #1 would it be better to run-in the engine the engine with extra castor in lieu of turbine oil, or just start out with the turbine mix? #2 And is the turbine oil even a good idea at all, just run extra castor?

This engine will be used with a prop, not a fan, and will be run-in with a cut down wood prop as well. The engine's piston will be moved to the bottom of stroke and the head heated just prior to the first run. It be ran at rich WOT asap to get it up to temp.

downunder

Personally I'd go with the extra castor to bring the standard fuel up to the 23% mark for running in and flying. I've used jet oil (Mobil Jet Oil II) both as the only oil and as a blend with castor and it's worked fine, admittedly not in a high performance engine though, but I believe jet oil is common practise in ducted fan engines. Probably the best jet oil for our use is the BP 2380 which doesn't have the heavy brown dye used in the Mobil oil which can leave stains on the model's finish. Although the jet oil worked great I went back to castor because it's so much cheaper.

A word of caution on the Mobil jet oil, only second generation works because third generation isn't soluble in methanol.

freakingfast

My Feedback: (3)

Thanks about the tip on solubility. Been down that road before and ruined a few gallons of glow fuel. I needed to be reminded.

Sport_Pilot

Many Turbine oils have some hazardous materials.  I would read a MSDS sheet on them before using.

downunder

If you want a real scare then read up on methanol .
As an aircraft engine fitter I've been immersed in jet oil up to my armpits for many years and even with the military's concerns for safety we didn't need to take any extra precautions. Normal common sense like not drinking it or breathing in exhaust fumes is all that's needed. The unburnt methanol in the exhaust is what you really have to be careful with.

freakingfast

My Feedback: (3)

Thanks for the health warnings guys. Years of exposure to smoke coming off hot parts (zinc, cadmium, chromium, oils, solvents and God knows what[:'(]) I'm not too worried about catching brief whiff of smoke from an RC engine. Dang CA fumes will get me first.

kenh3497

My personal opinion is to use the caster. Proven for the last 100 years or so to be one of the best lubes for model engines..... Well maybe not a hundred years

Don't run the engine to rich. A fat two cycle is all that's needed. Use the MFG's recommended prop for break in.

Ken

Sport_Pilot

It also depends on which oil. Not all have hazardous substances.

Sport_Pilot

Some turbine oils are fine, your milatary may not have used the more exotic ones, at least for the aircraft in use.
Also full scale planes don't spew as much oil out the exhaust.

downunder

Most of my work was with Mobil Jet Oil II on the F111C so I don't know what our exotic aircraft used .

Sport_Pilot

Thats not one to worry about.  Maybe its the stuff they use on the stealth fighters.  I know I have seen some bad MSDS sheets on some other jet oils.

freakingfast

My Feedback: (3)

Must be getting old.
I bumped into a full bottle of SIG Castor oil and full bottle of SIG Klotz that I forgotten about. So I'm skipping the turbine oil to use what's on hand.

I just picked up a new gallon of Powermaster 15-17. I bumped up the oil with 5.4 oz of Castor and 4 oz. of Klotz for a new total of 23% oil.
So I now have 14-23 fuel. I added a .005" head shim because these engines are set for 10% nitro.

There was still a fair amount of space left in the can so it could be shaken well. Do you think this mix will stay in suspension, of do you think I should add a oz. of acetone?

1QwkSport2.5r

I've mixed up a "break-in brew" of 5% nitro and 25% castor and it stayed mixed just fine. I think Fox still makes a fuel (I forget the name of it) thats 29% castor. I'm sure you'll be fine without adding any extra solvents to it. If anything, let it sit for a week and look at it in the light. It would be pretty obvious if any of the oil settles out of suspension.

On a side note (don't mean to hijack!): Does anyone know what the max oil content would be for methanol to hold it in suspension?

freakingfast

My Feedback: (3)

I'm a bit paranoid, I once added some two stroke oil meant for gasoline engines (weed whacker- outboards ) and it ruined the gallon of glow fuel. Globs of goo floating around, refusing to mix in. Didn't realize it till I was trying to get the engine to run right at the field. No joy, no chance.[&o] Never again.

1QwkSport2.5r

I tried that with some leftover Amsoil synthetic outboard oil (about 1/2 ounce) mixed with methanol and it turned cloudy and within 3-4 days it settled out. There aren't many oils (petroleum or synthetic) that mix with methanol. Supposedly you can get petroleum oil to mix with castor oil if you heat the castor oil up good and then mix it with glow fuel but by doing this you destroy Castor's ability to polymerize. Not a gamble I'm willing to try. Oils designed to mix with methanol (synthetics I mean) are pretty darned expensive. Klotz is something like $50 a gallon and one online retailer that sells motul micro wants $75 a gallon. Motul Micro is an ester oil wheres Klotz is a PAG oil AFAIK.

I think there is a threshold where too much is too much and it will settle out. There was a post earlier this winter about a guy running 1/2A engines and mixing lots of nitro in the fuel and it seperated. Then acetone is the ticket.