Author Topic: 4-stroke oil question (Read 4041 times)

Larry Renger · « **on:** February 11, 2008, 09:30:47 AM »

As I recall, it is recommended not to use any Castor oil in 4-stroke engines. My question is "Why?" On all my other engines, I use a 50-50 mix of Castor and Synthetic, and they all seem very happy with it.

Bob Reeves · « **Reply #1 on:** February 11, 2008, 09:40:48 AM »

I believe it's mainly a viscosity issue, castor being a much higher viscosity than synthetic. Four Strokes need all the help they can get with fuel draw and thinner oil simply flows better. Some have even gone to special low viscosity oils.

Not sure what oil Powermaster YS 20-20 uses just know it works and it's all synthetic. After run oil is a must with all synthetic but small price to pay for fantastic engine preformance.

Bob Zambelli · « **Reply #2 on:** February 11, 2008, 10:18:31 AM »

For what it's worth, I use Brodak 10-23, 50/50 in ALL my glow engines.

4-stroke, Foxes, vintage, ringed, lapped, ABC, AAC, ABN, whatever - same brew for all.

I use Winsor Lube L-245X for after run and long storage. It's absolutely the best thing I've found.
Meets MIL-L-6085 and MIL-PRF-6085.

Bob Z.

Ralph Wenzel (d) · « **Reply #3 on:** February 11, 2008, 10:26:52 AM »

Hi Larry,
My 4-stroke experience is not extensive (at all), but Saito recommends PowerMaster "YS-20/20", which I believe is all-synthetic. They seem to thrive on this blend. We fly at Sea Level, too - - roughly +20 feet.

Bob Zambelli · « **Reply #4 on:** February 11, 2008, 02:05:24 PM »

Hi, Ralph. Is that reccomendation for the newer SAITO engines? I remember reading the instrucions quite a few years back but I don't remember mention of YS blend.

I know that a lot of people use it but 20% nitro just seem too high to me.

Bob Z.

SteveMoon · « **Reply #5 on:** February 12, 2008, 07:09:46 AM »

I have been flying 4-strokes for several years now, and I would definitely
NOT use any castor in these motors. My buddies that fly 4S motors in
RC Aerobatics will confirm this. They NEVER use castor in their motors, it
just isn't necessary, or even recommended. Bob R. is correct, one of the issues
is viscosity. 4S motors need a fuel that will flow more freely. Also, modern
motors in general (and particularly 4S motors) do not need castor due to
the much finer machining tolerances and higher quality metals used these
days.

Saito does recommend using Powermaster YS 20/20 fuel. This is a newer
blend that has been on the market for maybe 7-8 years; not sure exactly.
I've used the YS 20/20 fuel in Saitos, OS motors, Enya motors and YS motors
and it is excellent. I always get consistent runs and have burned several
cases of this fuel.

Later, Steve

Bob Reeves · « **Reply #6 on:** February 12, 2008, 07:38:18 AM »

Bet you noticed the conflicting replies.. I don't believe either is wrong but based on what the person is wanting/expecting out of his engines. I need all the help I can get and spent a conciderable amount of trial and error time making my four strokes help me fly a competitive pattern as best they can. Bob Z can take a setup I wasn't happy with and whip my butt simply because he can.

Guess the right answer is whatever works for you but don't be afraid to try something different if what you are doing isn't producing the results you are expecting.

Larry, please go to your profile and delete your zip code.

SteveMoon · « **Reply #7 on:** February 12, 2008, 04:20:03 PM »

Actually, I've just been on the phone with one of my RC buddies
that flies 4 strokes and told him about this thread. His reply: NO
castor. A 4S motor only needs enough oil to lubricate the parts.
In a 2S motor the oil is also vital for cooling. Not so much with a
4S motor. Also remember that in a 4S motor only every other
cycle are certain parts being used. So, they only need enough oil
to lubricate them through each cycle.

Steve

PeteBergstrom · « **Reply #8 on:** February 12, 2008, 04:53:57 PM »

From the Saito point of view, the reason we don't recommend castor is simple.

If/When you get varnishing from castor this always happens in the hottest spot in the engine. On any engine that tends to be the exhaust port. A four stroke exhaust port has a valve in it, that has to slide smoothly through the valve guide. Castor has a tendency to cause varnish on the shaft of the exhaust valve, causing the valve to stick in the valve guide, ultimately the exhaust valve does not seat properly and you lose compression, the engines starts to run lean or at least lose power.

If you do have some accumulation of varnish you can remove it from the shaft of the valve, and the valve guide and the engine will be restored to normal operation.

Pete
Saito product manager
Horizon Hobby

Steve Helmick · « **Reply #9 on:** February 12, 2008, 09:06:17 PM »

FWIW, the Powermaster 20/20 has been called "YS/Saito 20/20" for several years. It's great mixed with Powermaster's 10-29 GMA, too. But not for 4 strokes.

Hay, Pete...flown any helichoppers lately?

Steve

Bob Zambelli · « **Reply #10 on:** February 13, 2008, 07:24:16 AM »

OK, you fellows have really got me thinking about lube.

Yes, I have been using 50/50 castor/synthetic but maybe I'm on borrowed time (?)

Maybe it's time to rethink knowing the (possible) consequences as outlined by Mr. Pete.

To explain my statement about borrowed time, consider, among others, the SAITO .30 that I fly on my Little Cherokee. I bought the engine as soon as it came out, (Maybe 9 years ago?) and ran it exclusively on 50/50. Even though I do not keep a flight log, my best guess is that it has well over 600 flights.
The valves were adjusted after the first hour or so of run time and have never been touched since.
The glow plug has never been removed. I have no clue as to what type it is - it came with the engine.
Once broken in, the run characteristics of the engine HAVE NEVER CHANGED.
My Argus, also powered by a SAITO 30 is closing in on the Cherokee regarding flight time - a number of you have seen it fly. It is PERFECT, at least for my needs.

The only 4S engine that failed catastrophically

was my Surpass .40. Purchased used from an RC flyer with God knows how many runs, it just blew up one day. Crankpin broke and took the rod, case and piston with it. BUT, there was no sign of lubrication failure - no scoring or seizing anywhere.

So, what to do?

??

Bob Z.

Scott Hartford · « **Reply #11 on:** February 13, 2008, 08:50:39 AM »

I run my 4 strokes on powermaster 15%. The Y/S 20-20 is just too expensive. I think you may have a problem if you ran ALL castor, but wouldn't some (more than half in most) synthetic in the fuel keep things clean? I figure the savings in fuel over the life of the engine would pay for a new one if it broke....

Larry Renger · « **Reply #12 on:** February 13, 2008, 10:21:01 AM »

Great info, guys, Thanks! Especially the part about varnish on the valves. I'm with Bob - much to consider.

tom hampshire · « **Reply #13 on:** February 13, 2008, 10:34:29 AM »

My experience with a Saito 72 leads me away from castor. It was my first attempt with 4 stokes, used 10-11-11 powermaster stunt fuel and settings which were way too lean, along with a flat pitch prop. At about 100 runs the rod seized on the crankpin and broke. There was ample evidence of lubrication failure everywhere in the lower end. Not only is the varnish a problem, but the superior film strength of the castor is the last thing needed where the lower end is lubricated by blowby only. I'd vote for synthetic oils alone, because you need a limited amount of blowby to get any lubricant to the lower end. The castor tends to seal up the piston skirt and block oil flow. Kudos to Saito as well for excellent post sale support. Tom H.

Andrew Borgogna · « **Reply #14 on:** February 13, 2008, 11:42:38 AM »

Pete's explanation for not using any Castor does make sense but I would add that even a small amount of synthetic oil will help keep the varnish to a minimum. At least that is what I have been told, it's the reason even Fox now adds 3% synthetic oil to their fuels. So maybe the reason Bob Z. does not have problems is that half the oil is synthetic and it keeps the varnish from forming. This is just a guess and not based on any empirical data.
Andy

Bob Zambelli · « **Reply #15 on:** February 13, 2008, 12:59:02 PM »

What a great discussion!!!

It really adds new meaning to the phrase "Individual results may vary"!!!!!

Bottom line, as always is whatever works, stick with it.

More note of interest. When Windy was evaluating 4S engines, he fitted a Surpass .70 and then later a SAITO .72 to his Tradition. He used Powermaster 10-22 exclusively and each engine had well over 300 flights. Never a problem.

I have some friends in Italy who use 4S engines. One fellow flew his Surpass .70 for four years using 25% castor, ZERO synthetic. It was the first big 4S plane I ever saw and it was amazing.

I do not concur regarding castor inhibiting/preventing blowby - were that true, I would have a lot of scrap metal on hand.

OK, more "fuel" for the fire. A friend flew a semi-scale plane with a SAITO 40A. One day, the engine stopped expensively - you know, that kind of stop where you KNOW something broke and it's not gonna be cheap!

When I disassembled it, I found the inside dry - completely dry as if it had been cleaned with alcohol. Not a sign of oil ANYWHERE. Furthermore, there was not a sign of lube starvation anywhere. Not a scuff on the piston skirt, no galling on the crankpin - NOTHING. The bearings turned smooth-as-silk without a rattle. The cam/tappet interface showed minimal wear.

So, why the abrupt halt? As you may know, the SAITO cam is driven off the crank by a 1:2 spur gear combo. The cam turns on oilite-type bushings. Close examination of the gear showed that a tooth had broken off and wedged between the remaining teeth and the lifter boss, making a small nick in the casting.

That was the only damage. I replaced the cam and lifters as well as the ring and it now runs like new.
Fuel used? As far as I know, straight synthetic, 10% nitro.

Go figure!!

Bob Z.

As fa

Scott Hartford · « **Reply #16 on:** February 13, 2008, 01:29:58 PM »

Also, if you used after-run oil (you DO use it, don't you???), wouldn't this clean any varnishes up pretty good? Besides, castor makes better smoke trails, and who wants to fly with no smoke?

Dave Adamisin · « **Reply #17 on:** February 14, 2008, 10:24:56 AM »

Heck this is easy for me. I swore off castor in the early seventies and have never looked back. No angst, no varnish, no internal conflict.

Leonardo.STUNTI · « **Reply #18 on:** February 14, 2008, 02:08:32 PM »

The lube used (castor/syntetic) have relationship with work temperature? thanks

tom hampshire · « **Reply #19 on:** February 14, 2008, 02:43:55 PM »

In short, the castor has better film strength at high temp. For the whole story, read and memorize Randy's fuel article at the top of the Engines column. It's required for us all. Tom H.

Dave Adamisin · « **Reply #20 on:** February 14, 2008, 05:53:25 PM »

Quote from: tom hampshire on February 14, 2008, 02:43:55 PM

In short, the castor has better film strength at high temp. For the whole story, read and memorize Randy's fuel article at the top of the Engines column. It's required for us all. Tom H.

Film strength at temps that are irrevalent to engines isn't an advantage. The oil has two jobs: lubrication - floating the parts so they don't touch, and cooling. Not cooling as in carrying away heat as it leaves the engine, but passing along the heat from one part to another, as in from the piston to the liner to the fins. My objection to castor in this capacity is that the varnish it forms inhibits both lubrication at relevant temps and heat transfer. If an engine gets hot enough to need the protection varnish is supposed to posess, it's in trouble anyway.

RandySmith · « **Reply #21 on:** February 14, 2008, 11:04:08 PM »

Quote from: Dave Adamisin on February 14, 2008, 05:53:25 PM

Film strength at temps that are irrevalent to engines isn't an advantage. The oil has two jobs: lubrication - floating the parts so they don't touch, and cooling. Not cooling as in carrying away heat as it leaves the engine, but passing along the heat from one part to another, as in from the piston to the liner to the fins. My objection to castor in this capacity is that the varnish it forms inhibits both lubrication at relevant temps and heat transfer. If an engine gets hot enough to need the protection varnish is supposed to posess, it's in trouble anyway.

HI Dave

Your are absolutely correct ..in a perfect world..All synthetic will work great given the proper amount\percentage of oil. And if the needle is always set correctly and nothing ever happens to mixture in flight.
Problem is ,we all have seen the... uh oh .. 15 minute ultra lean burn down flight from a needle that moved, or trash in the spray bar to whatever. many times the added Castor will greatly help in this case.
The synthetic that most all fuel mfg. use will tend to flow away from ultra hot metal where the Castor will plate it.
It may burn to a hard varnish that is also harmful to the engine..but it will help protect the motor.
This is one reason why I never use all Castor fuel in anything. I even have FOX 35s that are over 35 years old I ran in 1970 that used part Castor part synth fuel..they are still excellent today.
I personally use a fuel that is 19% total oil with 75% of that being synthetic. This has worked for me for many many years.
This would be in a modern AAC or ABC ball bearing engine.
For motors like the FOX 35 and OS 35 S , or any of this type I use a 25% blend with 50% Castor.
4 Cycles are a little different story and I included my finding about fuel in the articles also.
I have gone thru a great deal of experimenting, testing, reading, and trying to learn all I could about what is the best mix to use over the course of a little over 3 decades ... I have given up trying to convince anyone that , for example..FOX 35s *had* to use all 28% Castor fuel only.
I have relayed most of my data and what I have found from many many test. But I know people are going to use whatever mix they think , in their mind, to be the best.

Regards
Randy

Dave Adamisin · « **Reply #22 on:** February 15, 2008, 08:53:14 AM »

Quote from: RandySmith on February 14, 2008, 11:04:08 PM

HI Dave

Your are absolutely correct ..in a perfect world..All synthetic will work great given the proper amount\percentage of oil. And if the needle is always set correctly and nothing ever happens to mixture in flight.
Problem is ,we all have seen the... uh oh .. 15 minute ultra lean burn down flight from a needle that moved, or trash in the spray bar to whatever. many times the added Castor will greatly help in this case.

Hi Randy. I have been doing this for a while and so have had my share of ...uhhh.. fuel flow issues. If you ever flew rat race you really can identify with a burn down.... a 60% nitro burn down. It is these burn down runs that convinced me that the "back up parachute" of castor didn't exist. After we switched to synthetic (ucon) the victims of the burn down were much easier to revive. I believe it was because the parts never got as hot in the synthetic engines because there was no varnish to insulate the parts. Cooling in those cases was more important than theoretical lubrication.

The synthetic that most all fuel mfg. use will tend to flow away from ultra hot metal where the Castor will plate it.
It may burn to a hard varnish that is also harmful to the engine..but it will help protect the motor.
This is one reason why I never use all Castor fuel in anything. I even have FOX 35s that are over 35 years old I ran in 1970 that used part Castor part synth fuel..they are still excellent today.

Same here. We didn't leave the FOX's out on a limb..... K&B 100.........

I personally use a fuel that is 19% total oil with 75% of that being synthetic. This has worked for me for many many years.

Randy I'm not saying it doesn't work. I'm jusy saying that synthetic has worked better for me. There are many roads to China. Funny thought just hit me. We found that the best use for castor fuel was to use it during break in especialy in engines that just wouldn't get hot enough to make the piston grow. A couple runs with castor would get the piston crown hot enough to grow and then it would be back to the regular fuel for the duration.

This would be in a modern AAC or ABC ball bearing engine.
For motors like the FOX 35 and OS 35 S , or any of this type I use a 25% blend with 50% Castor.
4 Cycles are a little different story and I included my finding about fuel in the articles also.
I have gone thru a great deal of experimenting, testing, reading, and trying to learn all I could about what is the best mix to use over the course of a little over 3 decades ... I have given up trying to convince anyone that , for example..FOX 35s *had* to use all 28% Castor fuel only.
I have relayed most of my data and what I have found from many many test. But I know people are going to use whatever mix they think , in their mind, to be the best.

Regards
Randy

I coudn't agree more. This is a forum for opinions and info sharing. My ideas about model engines and lubrication come from my experience with them and from years (36) of working in engine design at Ford. I had many discussions with the lub guys and we actually tested some castor and ucon in wear fixtures at various temps and I decided (everyones mileage will vary) that the best compromise was synthetic.

Thanks for taking the time DaveA

proparc · « **Reply #23 on:** February 16, 2008, 10:02:02 AM »

All my 4 strokes run with Castor or they don't run at all. In fact, all of my engines run with some castor period. I have had my 72 apart plenty of times and I know what the exhaust valve looks like after all of those years of castor. No big deal!! I just cleaned the valve with a Scotch Brite pad once and that was it. Saito's have some really nice internals and you want to "baby" those parts with some castor!!

I honestly believe that one of the main reasons my engines last so long( my ST46 stills runs perfect,I got it when I was 14 years old-ask Jose Modesto), is the use of no-nonsense good quality fuel. In addition, I don't use a separate fuel for my 2 and 4 strokes. One fuel for everything. I don't buy commercial fuel. I have my fuel made for me and I strain once I get it. Control line stunt is about attention to detail. Sweating the details in large part, determines the success or failure of your overall stunt program.

john e. holliday · « **Reply #24 on:** February 16, 2008, 08:31:52 PM »

As stated many times, what works for one may not work for another. So you try it. If it works you stay with it. If it don't then you file it away as it may work next time. Everybody has their way of doing things. DOC Holliday