Mikko Moi!

In F2C, the 927 is very popular. I guess the team race guys were the first who used it. So, it's probably the best castor based oil at the moment.
I know people mixing it with a small amount of Benol, to get that healthy tan on piston crown, otherwise it burns *too* clean!
So the answer is, both will work well with your PAW. L

Klotz Benol runs just fine. I've run it in sport engines and F2C engines. With Maxima 927 oil, you are getting a mixture. Their literature says it contains "exotic esters."

https://maximausa.com/rt-6004-2-stroke-powersports-engine-oils.html

If fact, according to data that Maxima was required to file for hazardous material evaluation, 927 contains 50-70% castor, less than 50% ester, and 10-20% multifunctional additive mixture. The percentages are intentionally vague since they are claiming a proprietary formula. Unless someone has done a spectrographic analysis, we are unlikely to find out the exact proportions or constituents.

https://maximausa.com/files/datasheets/sds/castor-927-sds.pdf

If the "multifunctional mixture" contained a burning component such as alcohol or kero as a solvent, then per tank, the F2C guys might see a range improvement which is a really big deal. But the reality would be that they are simply running less lubricant. As long as their rod bearings are holding up and the piston/liner wear is acceptable, that is a good tradeoff. One large advantage is that the oil should help keep the piston, liner and head/contrapiston cleaner, and what carbon does build up should be softer. The fewer times you have to tear down the engine just to get the carbon out, the better.

Use what works--but if you are trying to run a small percentage of lubricant, be aware that perhaps a significant percentage of 927 is not actually oil.

A final comment:  F2C engines are very finely fit, ball bearing units. And, if the engine tune goes hard/lean, they are instantly shut down for an adjustment. A PAW sport engine may be a plain bearing setup which has different lubrication requirements. You are also not likely to be running it within an inch of its life...but would prefer that it run nearly forever, even if you get a bad compression setting and find out after it is in the air. Just a few thoughts for your consideration.

Dave

Yesterday I made a following mixture:

25% Klotz Benol
33% ether
40% Jet A1
2% Red Line Diesel Plus 85

This simply didn´t work. I had a little amount of running-in fuel left, there was 30% Castrol M, 33% ether, 35% kerosene and 2% DII. I tried it and it worked fine. Today I tried Maxima Castor 927 as Lauri recommended:

30% Maxima Castor 927
33% ether
35% Jet A1
2% Red Line Diesel Plus 85

So, it was like the old running-in fuel, but different oil and DII. This works! Perhaps I had too little oil or the Klotz Benol does not work in my PAW .40 TBR.

The tank size is 80 ml, made according to Freebird plans. It gave me 6'30"-7'30" running times, prop was 11"x 8" Master, 7500-8000 rpm.

Mikko

Yea , ' Mills fuel used to be 3 equal parts , 33.333 % each . and it worked .

A bit irrelivant , but Id run a  litre & a quater through a Veco 19 , of 30 % oil .
Threw it in the Twin Mosquito & headed out with 25 % oil juice . It didnt want to know . Ran like a wet rag .

Back on 30 % it ran fairly hard . After that , 2 1/2 litres fed through it , it was o.k. on 25 % , but ' improved '
further with more flights . Three to go steady . And Id thought it'd give it a easy time , free cooling , outboard - backed off , in the Mosquito profile .

APPARENTLY Earlyer Super Tigres were TIGHT , and needed a few hours ' bedding in ' before flight . Annoyed to many people , so they did em less good afterward .

SO , if its ' Good & Tight ' , a protracted care & consideration should see a long and happy life .     

INDEED .

a few fings with diesels ,

Learnt from a PAW .09 that ' wouldnt go ' in winter. the BOOK said THREE TURNS . on the needle .
after 45 minutes one day , without luck , perhaps after two hours the day before . STUFF IT .

Exhaust Prime & give it a burst , to find ' compression ' that it fires on ! . Needle Closed .
Repeat at ONE turn,
Repeat at two turns ,
repeat at three turns ,
repeat at four turns,
repeat at five turns , bbringg bringg bringg , or whatever .

Three turns on the needle , as per instructions , you woulda been there the chrismass after next , till it RAN . From being run in from being belted over .
You BELT diesels over , and see theyre Not Flooded , first . .
o.k. , wants to be rich , and tank just high enough to gravity feed intake . Not to Low where the fuel tubes empty .
Clear Neopreen rather'n the black rubber non see thru , too .

PROPS : all the drivle rattled on about NEVER overproping them . Little light props are no flywheel effect . a inch or so UP , are heavier .
so a 9x4 on the little PAW .09 , rather than the stated 8x4 , itll START twice as easy . Particularly when its TIGHT .
But youll overheat it ! ( they say ) . Bollocks ! I say , IF the Comp. is backed right OFF , and the needles comesurately a few more turns OUT ,
It'll tick over nicely blubbering away happilly , with plenty of COOLING fuel going through . So as Half as HOT as the recomended proceedure .
Or Cool , Man .     

Obviously , if you wind up a new motor on a big prop , it's gunna overheat . Same as itll run frazzling hot on a little prop wound up , when new .

The drivle in yonder years was ' blah blah mateing surfaces , blah blah microscopic ridges , blah , matching, blah . Only ever fit one way , blah . etc .

A B C 's are differant . Completely , particularly A B C twin ball race diesels .

STD Plain or single bearing iron piston devices want ' bedding in ' conservatively . NO HOT SPOTS . When Tight , the higher initial mating bits , expanding ,
can stick . Some call this Siezing , Galling , ' Picking Up ' and suchlike .  So a few quite steady rich runs , bare fingers periodically grasping the FINS , and
checking the shaft bearing housing , shutting off when past touchable ( 90 Deg ) .
FIRST starts mayybe just prime BURSTS , as stated . And a few V Short 10 then 30 second ' blasts ' , if its as heath robinson as they seemed to believe ,
see ' nothing catches ' before its " knocked the high spots off '  , settled in , and starts to ' condition ' its running surfaces . unwraught & undistressed ! 

Something like a RVD would go on a 8 x 4 after the first say six runs ( way backed off ) to singing along , backed off , on a 8 x 4 . But not alf as backed off as youd get it on a 9 x 4 . 

SO , Common Sense , really . But They WROTE a Lot Differant . Pipe Puffing Hillocks .  DONT Wind It UP , or TRY , till its RUN a half hour . Better Two Hours . BRIEFLY .
The '" see if it holds " check . Like the fool toob pinch . But UNHURRIED is maybe better . A SPORT FLYING engine , as opposed to Competition , might never necesarilly be ' thrashed ' .
Your Grandmother may not go as hard as Mario Andretti . Ever  . Her car might be like new . His may not .

What characteristic did you see in your batch of fuel that "...just didn't work"?  Poor starting? Non-starting? Wouldn't hold a setting? Wouldn't adjust to a useable setting? Overheating and sagging?

Poor starting was the main problem, and after I succeeded to start it up the running was poor and rough. It didn't reach the same rpm as with the old fuel and the rpm went up and down, up and down. When I tried to start it did not fire at all, I had to put more and more compression before it fired.

The critical element here may be that you are still breaking in your engine. In which case oil is critical and one engine may take more running than another.

I thought this engine is fully broken-in because it started so easily and was easy to set up, so I made a mixture that the manufacturer recommends to fully broken-in engines. It may mean that this one does not be ready yet and I have to continue running in. I can do rest of it by flying when I first get my Freebird ready. There is still a lot of work to be done before it flies.

Another thought: before I threw out the first mix, I would bump up the Benol to the same 30% number you are using for the Maxima and try it again--if the issue was that it was overheating, even at lower compression settings. There's no reason that Benol "won't work" in a PAW. That's not just based on my experience--if you look at Eifflaender's site, he recommends castor fuels. And, as Lauri suggests, the factory fuel chart shows that as break-in is completed, the oil percentage may be reduced on a twin ball-raced engine.

I'll increase the oil amount in my first-made mixture, the problem probably was too low oil percentage.

By the way, a friend of mine found a product description of the Red Line 85 Diesel Plus. According to it there is only 20-40% 2-ethylhexyl nitrate, which is the ignition improver I want to use. Now I had only 2% Red Line in my mixture, I should put it about 6-7% to get 2% 2-ethylhexyl nitrate in my fuel.

Mikko

I’ll add another vote for Klotz Benol. Works perfectly fine. I’ve also used plenty of Cool Power castor which too works just fine.