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Oct 11, 2012, 09:31 AM
Registered User

Double Duty Fuel

As far as I know the only difference between 2 cycle and 4 cycle fuel is the (castor) oil content.

Can you use 4c fuel in a 2c engine, with the understanding that there will probably be more slobber to clean up at the end of the day?

Can you use 2c fuel in a 4c engine if you add some kind of oil to it?
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Oct 11, 2012, 10:10 AM
Registered User
Your are right on both counts. The required percentage of oil for 4 strokes has been debated for some time. O.S. said to just use 2 stroke fuel although their engines will perform better at idle (for example) with 12 to 16% oil.

One thought for all of us here: How many engines have you actually worn out? I can think of only one in my case (an OK Cub) that was obviously a lemon as it was running on 20% castor oil fuel in cool and non dusty conditions.
Oct 11, 2012, 10:10 AM
Registered User
I've been using 10% 2-stroke glow fuel in my saito and OS 4-strokes for about 14 years with no problems. Same fuel I use in my 2-strokes. I tried the more expensive 4-stroke saito/YS 20/20 fuel, and naturally it ran a little better, but the cost just wasnt worth it. I dont tune my engines for every bit of power I can squeeze out of it. I have four saito 1.20's and two with well over 200 hours run time still with all original parts, including bearings. I tear them down around every 60 hours for a good cleaning which includes taking the valves out and cleaning all the carbon out including the intake and exhaust ports.

Forgot to mention, its Power Master.
Oct 11, 2012, 11:02 AM
Dieselized User
gkamysz's Avatar
Most 2 and 4 strokes engine do fine with 18% oil. If you don't want to use different fuels just use something with 18% oil.

Oct 11, 2012, 11:11 AM
Registered User
Power Master changed the formula on their 10% 2-stroke a few years back (when they were sold). It used to be 18%, now it says 17%. Havent noticed a problem in two years of use.
Oct 11, 2012, 11:32 AM
Dieselized User
gkamysz's Avatar
Sure, 1% isn't really going to make a difference, needle setting has more influence. I run low oil content in most my engines. But I don't recommend it to others, it just draws blank stares.

OS recommends 18% oil in all of their engines. How many of their car engines get run on 18% oil? Probably few to none. Most car fuels have 10% oil.

Oct 11, 2012, 11:59 AM
jeffie8696's Avatar
I use 18% oil fuels in my 4S engines and ball bearing 2S engines but prefer 20% oil in my bushing engines. And all my engines are super happy.
Oct 11, 2012, 04:41 PM
the great Gassif´er
My only fourstroke to date does its job in an helicopter, for little over 10 years now, and it is running on 10/10 full synthetic.
Changed the crankshaft bearings after the first season, and never again until now, adjusted the valves maybe 3 or 4 times in all those years.

Would not want to use that mix in my 2 strokes though....

Brgds, Bert
Oct 11, 2012, 04:53 PM
Registered User
I use 10% Nitro Coolpower in all my glow engines
Oct 11, 2012, 04:54 PM
Registered User
I use 10% nitro, 20% castor in ALL my glow engines. 2 or 4 cycle. Have been since I bought my first 4 cycle in 1976. Prior to that I ran K&B 100 in all my glow engines. It was 5 % nitro and 20 % castor.

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