SAVAGEJIM

I know this has been beaten to death, but in an effort to get all the info on 2stroke oils, I wanted to attempt to collect all the info and summarize it in one thread instead of this subject being spread around in 20 or so separate threads.

First and foremost, I want talk about oil ratios to gasoline.
Every RC maker that makes gas RCs say to use a 25:1 gasoline to oil ratio.
Some others say you can go as little as 32:1 or even 40:1. I have gone as low as 32:1, but I never have had the heart to go 40:1.
Also, I have hear of gas and airplane guys going as high as a 12:1 ratio, which I personally think is too damn much, but I guess for their applications, they must have that high of a ratio.

Now to different types of lubes.
The first, of course, is good old castor, which I assume is what the gasser RC companies assume when they recommend the 25:1 ratio.

And of course, there are your synthetics. But I admit, I am lacking in knowledge in these, other than that they tend to have superior lubricating attributes than castor throughout a wide range of conditions.

This is where I need the more knowledgeable people to begin to add on and post their knowledge about castor and synthetic lubes. Please do pos, even if you mentioned it earlier in various other threads, I want it summarized here, so I can learn, and also, hopefully others can too.
And if you do know technical information concerning lubes, I definitely want your input.

splcrazy

well okay , this is what ive been upto this week actually, for my 5b , i was first using klotz castor but stopped cos it was making a hard baked on crust on top of piston , then switched to a different brand called FUCHS 2t motorbike oil , which was okay but too damn thick causing multiple fouled plugs at a ratio of 25to 1 i may have to go thinner than 25/1 with that brand but i didnt , so i have now gone back to using what i have always used for years without problems and its called CASTROL full synthetic 2stroke for motorbikes for high reving engines , and can tell its running alot better now but the engine turned off twice maybe cos i got the motor too hot i dont know , i put in a brand new plug on it too . So if you ask me i will tell you to run full synthetic no castor

Johnnysplits

I'll throw one in too. I use Redline Racing 2 stroke synthetic race oil. This is the best IMO. Dyno proven to give 2 to 5% power increase, and the CY26 that's in my boat shows absolutely no wear after two seasons now. That engine runs at 18,300 rpm constantly...and I can't even tell you what rpm it goes to when the boat feels like being an airplane. Awesome stuff. Go check it out on their website and read all the technical data...you'll be impressed.

SAVAGEJIM

Thanks of the info.

I always hear that; synthetics allow you do go with a much smaller ratio, even 40:1 or 45:1 or much less. But my concern is what kind of residue is left after it is combusted?

I know that lube breakdown is not a concern in two-stroke engine because fresh oil is always entering into the engine because it is mixed with the fuel, even in high temps, the fuel and oil have a quenching effect somewhat, but what the synth polymers breakdown into after combustion is a different story.

Just like you mentioned, residue builds up in the cylinder; namely in the combustion chamber and piston surface because the piston ring cannot scrape those surfaces.

Johnnysplits

You can play with spark plugs of different heat ranges.

SAVAGEJIM

Good to know, especially for boats and airplanes, they see much more constant max RPMs than cars and trucks do. Cars and turcks will spend little time at max RPM really, but airplanes and boats do remain at top RPMs for much more of their operation.

As for your oil ratio, do you use a much higher oil ratio? Like as high as 12:1? If so, what would be the reasoning? I of course presume it is because your boat engine remains at top RPM for much more of its time than a car/truck engine would.

Johnnysplits

I run the boat mix at 16:1 (8oz. per gal) That ratio is working out fine for me. Now when im done building my baja, i'll be running that mix at 32:1 (4oz. per gal) Like you said, the buggy will see max rpm for a short time hence no need to swamp it with oil which would be a performance killer.

mooman007uk

I run belray H1R full synthetic motorcycle oil, usually at 32:1 but running 25:1 for the first gallon in my new OBR 27.2 full mod...I'll probably continue at 25:1 with this motor seeing as it revs past 20K and a bit of extra oil has no ill affects just benefits when revving this high...never have any residue using belray either...very clean burn...the H1R is their best high performance race formula oil...amsoil is also excellent stuff and would use that if i couldn't get belray locally...i use amsoil in my cummins, tranny and diffs in my dodge great stuff...stihl synthetic is also top notch...i use that in all my other small engines...chain saws, weedwacker, leaf blower and pipe saws at 40:1 though they don't rev past about 10grand...higher it revs the more oil it wants in my book