my os50hyper runs on cool power heli ('pink' 30 and 'grape' 12.5 mix)...imho, cool power heli is a great fuel...no castor means zero staining of the muffler, but it might have some corrosive tendencies...my engine began sounding like a washing machine, which i knew from experience was a bad rear bearing...here's a pic of the bearing...i replaced it with a ceramic/ss race bearing from www.rc-bearings.com ...perfect and should last a lot longer...btw, the os50hyper is known to have a problematic rear bearing anyway (one of the biggest sellers for rc-bearings)...i'll continue to use cool power...ken

Just bought a gallon of Cool Power as that was all the LHS had in stock and was wondering about the synthetic oil only thing. Good thread, I guess I won't worry too much about running it though my Evolution .46 and .61. The thing is though, the jug says on it that NO after run oil is needed when using this fuel. Is that correct??

They might say that, and it may be true to a certain extent, but when I was racing 1/10th and 1/8th off road, I had 6 engines in rotation, before I started using after run oil (air tool oil) I would need to change a set of bearings every six months due to corrosion, I've never lost a set from rust since using the ATO. I also find the more nitro I used, the more susceptible to rust they become.

Luna_Rendezvous, Yeah, I thought I'd still use after-run oil regardless what the manufacture's claims are. Better safe than sorry!

Another good idea for corrosion protection and a alternative to after-run oil is FAI fuel. (20% castor 80% methanol) Just squirt a few CC's into your tank and run your engine dry, it gets rid of all the old nitro and it's residual acidic compounds and leaves a coating of lovely castor on the internals.

I just have to join this discussion. I can't understand the reason so many of you guys cling to castor the way you do. I don't have a bunch of theory or probability to support my conclusions....just real world experience. I beat hell out of my engines, run nothing but synthetic and have never had any problems I could blame on the lubricant. I have one Rossi 45 (Rossi recommends castor) that has seen a steady diet of 15% Wildcat fully synthetic, no additional head shims on a Tower Kaos with a pipe for three years...hundreds of flights...still runs like a raped ape. I have a Saito 100 that has run the same fuel for 2 years and shows no ill effects from the lack of castor. I have a Tower 75 that I have flogged unmercifully and basically treated like a red-headed stepchild for 3 years and it still screams. Modern synthetic lubricants are superior in every way to the traditional organically derived oils. YS engines are as cutting edge as anything out there (I have 4) and you can't run castor due to it's effect on the silicone parts in the regulator. Yet you don't see YS engines blowing up, shredding sleeves, melting pistons or grenading bearings. The US government spends tens of millions of dollars per on cutting edge jet fighters and you won't find a drop of organic or petroleum based lubricant in the things. I think its time to move on....


Rick

if you look back in this thread, I'm a dedicated Coolpower user, it's the only glow fuel I've used for the close to 26 yrs I've been flying RC, i run synthetic oil in EVERYTHING i fly, glow engines, gas engines and especially in my turbines but I'll be the first to disagree with that quoted statement.......

castor oil has one advantage that no synthetic oil that is currently available offers and that is it has the ability to save an engine in a lean run. I'm a left stick in the ON position kind of pilot so i go for maximum RPM but i also know how to set a needle valve so it doesn't go lean when unloaded in flight and i also know what it sounds like when one does. for those who set the needle for peak RPM on the ground and continue WOT when you can hear it leaning in flight, castor based fuels are the ONLY way they'll be able to keep an engine running for any significant length of time.

The difference is that synthetic is adequate as long as you don't go lean, on lean runs castor provides better protection. You may very well run all of your engines rich enough that they never encounter a lean run. As long as you do, you will most likely never have a problem. Many people don't have experience in proper tuning techniqes and as a result, run engines lean and damage them. Castor provides better protection in that case.

After all, what the heck would many of the engine manufacturers advise using a castor mix in their engines. You would think that after millions of engines they would have fiqured out by now that castor is totally useless. How many engines did you build before you fiqured it out?

If you don't like castor then don't use it but coming in here and acting like those that do use it is somehow less intelligent doesn't help your argument.

Hey, I'm not trying to insult you....I'm just trying to understand what physical properties castor has that can't be duplicated by synthetics. I do torture and abuse my engines and have certainly run them lean on occasion - but have just not personally experienced the type of damage I'm always being cautioned about. If I didn't have so much personal experience to the contrary I'd just accept the necessity of castor and use it.

Rick

No offence taken. Some of the things that God made, man can't duplicate very well.

For instance, for years man has made synthetic creams to help with sunburn. They help some but many still consider the best sunburn help to simply be pure aloe vera, cut from the leaf of the plant itself.

Applying this to the castor/synthetic issue, quite often, synthetic oil performs adequate most of the time, much like synthetic cream for sunburn and there's no issues but just like aloe vera, there are some properties to castor that no synthetic can duplicate.

While synthetics are fine so long as you know how to tune an engine and can perceive a lean run in the air caused by whatever reason (pressure line coming off for one) castor does have a couple of benefits. It tends to run towards heat (no, I don't know why), if it gets very hot it forms other lubricants where the synthetic falls apart and burns, and probably the major benefit in normal use is it's an exceptionally good preservative against corrosion. As for the cutting edge jet fighters, turbine oil is the only synthetic I've ever dared try in any of my engines.

It's because the viscosity index of castor is inferior to that of most synthetics.

The fact that it *appears* to run towards heat is *not* a good thing.

What happens is that the hotter side of a pool of castor undergoes a dramatic reduction in viscosity (which you *don't* want in an oil, better oils have higher VIs than poor oils). Since the hot side of the oil is now "runnier" than the cold side, the oil naturally flows towards that runny section because it is flowing away from the center of the pool due to the pressure of the cooler oil.

This shows two things:

1. The VI of castor is poorer than most synthetics

2. The thermal conductivity of castor is lower than most synthetics.

Now consider this...

Do you want an oil that maintains its viscosity when hot or one that gets runny as water?

Do you want an oil that conducts heat well and thus is effective at reducing the incidents of "hot spots" within the engine or one that tends to act like a heat-insulator, allowing hot parts to get even hotter?

Castor is a good lubricant but don't underestimate some of the modern synthetics.

You can run a good modern synth at ratios as low as 8% but I don't see anyone willing to do that with castor.

I wonder why that is?

And for the record yes, I do still run 2% castor in all my fuels. Why? Mainly for protection against corrosion (synthetics are still lacking a little in this area (note the title of this thread).