2 stroke oil, or top end lube ??

[Russ]

Ok, lots of guys are dosing their unleaded and 100LL with either of the above products. Both camps seem happy with results in their 4 banger engines.

 

I would be interested in hearing more feedback....both good and bad.

 

 

[M61A1]

I have used Moreys upper cylinder lubricant for years on 4stroke stuff, Several cars, Honda, Suzuki motorcycles and a Guzzi fitted to an aircraft. I've not had any negative effects, and my combustion chambers, valve stems and exhaust ports are always clean. But I haven't had a control sample to see what it would look like without it.

 

 

[AVOCET]

What ratio are you or they using , have been considering using a bit too.?

 

 

[jetjr]

Me too

 

Some guys near Adelaide were using Flashlube?

 

Never heard rates or solid success but was supposed to reduce ring sticking and cylinder rust

 

I did try another one.....MXO I think?? It may have caused some damage to inside of composite tanks. Used to get a few hairs in samples so stopped just in case.

 

 

[Russ]

One chap I know, runs pulp 95, with topend lube in his 2200 jab, to date he has around 1000hrs on the bottom end, 700hrs on top end.....still going strong. Mixes as per directions. Forgot what brand product he uses tho.....will chase info up.

 

Wasn't flashlube, moreys, but a cheaper one......common tho.

 

 

[Yenn]

I am surprised you got hares with MyXO, I thought it was designed for rabbits

 

 

[Russ]

Lucas......I tink

 

 

[turboplanner]

This information is very general only and designed just to show you possible trends with changes, and in no way is intended to be advice for non-qualified operators because of the potential for engine failure and its consequences once the aircraft has left the ground.

 

 

 

Nor am I saying what people have recommended above is wrong. I'm just suggesting you be very careful about modifying fuel, oil, or specification away from what has been extensively tested under load by the manufacturer.

 

When you change the viscosity of fuel, it affects the jetting, particularly the main jets which come into play at full throttle which is usually full load where the engine usually makes the most heat.

 

In racing I have seen many engines fail after someone having a problem with a piston seizure decides to add oil to the fuel for better lubrication. The engine seizes again, so he adds more oil to the mix, it seizes again, quicker this time, and still some add more oil.

 

What is happening in that cycle is that as oil is added to the petrol, the viscosity is lowered and the lower viscosity mix can't squeeze through the jets as quickly. Experts can take care of this by fitting bigger jets, however as I mentioned this is not something for the amateur to play with on an aircraft, where you can't just pull over to the side of the road and make another change.

 

In the case I've described the issue is more likely to be running too lean. A petrol engine sounds fluffy when rich, and as it is leaned out it sounds better and better and makes more and more power, but there is little warning when you go just that little bit too far, and a seized piston with a hole in the side of the engine or the top parted from the bottom of the engine is the usual result, again problematic.

 

Successful specification changes are measured in failure rate per one hundred engines, not just one goo experience with one engine, because the next engine with the same change can fail in minutes.

 

 

[jetjr]

Not sure 200:1 or less is going to chnage viscosity

 

 

[M61A1]

Not sure 200:1 or less is going to chnage viscosity

The recommended dose for the Moreys upper cylinder lube is 100ml in 65l, or 650:1. I suspect that the viscosity change would be quite minimal. Still, the plugs should be read regularly anyway.

 

 

[turboplanner]

Not sure 200:1 or less is going to chnage viscosity

Yes it will, and there's probably even a formula to calculate the difference, but the flow rate will change.

 

I agree it's minimal and I agree everyone should be reading their plugs anyway.

 

The difficulty is getting a clean cut on the plugs in an aircraft at main jet throttle to zero - hard enough in a car where you can have the engine pulling hard at full throttle, then cut the engine and throw the clutch at the same time. You'll still get some windmilling from the prop, so there will still be some masking other than for chronic rich or lean mixtures.

 

The $18,500 question is whether your skill set is precise.

 

 

[pylon500]

Not sure 200:1 or less is going to chnage viscosity

The opposite to this was happening 20 years back when some of the two stroke pilots began raving about a new super synthetic oil they were using, claiming it lowered EGT's.

Claimed it was so good, it could be run at 100:1 as opposed to the usual 40~50:1!

 

Turns out that at 100:1, the viscosity dropped enough that it made their mixtures richer thereby dropping the EGT's.

 

Didn't do their fuel consumption much good though....

 

 

[Downunder]

If 200:1 makes a difference and damages your engine, your already running too lean.......

 

 

[WayneL]

In the above posts....don't you mean Higher viscosity...... not lower viscosity when adding oil (thicker) to the fuel?

 

 

[turboplanner]

In the above posts....don't you mean Higher viscosity...... not lower viscosity when adding oil (thicker) to the fuel?

Princeton University - "What is viscosity?

 

"This question is often best answered by example. Imagine a styrofoam cup with a hole in the bottom. If I then pour honey into the cup I will find that the cup drains very slowly. That is because honey's viscosity is large compared to other liquids' viscosities. If I fill the same cup with water, for example, the cup will drain much more quickly.

 

Viscosity is a measure of a fluid's resistance to flow. It describes the internal friction of a moving fluid. A fluid with large viscosity resists motion because its molecular makeup gives it a lot of internal friction. A fluid with low viscosity flows easily because its molecular makeup results in very little friction when it is in motion."

 

Yes sorry Wayne, I had it back to front.

 

This definition also make it clearer to understand that for the same jet hole diameter, the higher viscosity of a petrol/oil additive mix will resist flowing through the jet more than pure petrol, so the mixture is being leaned.

 

In addition to this, something I didn't mention before is that the flash point of the fuel is lower, the burn will be slower, so timing is retarded, and this is also a heat producer in the combustion chamber. Again, I'm not recommending you fiddle with timing yourself, because the ability to blow an engine running on petrol at its optimum power output (leaner) is very very narrow.

 

Downunder you are probably correct, but how many people swap jets based on guesswork and finish up running right on the lean cliff?

 

 

[M61A1]

This information is very general only and designed just to show you possible trends with changes, and in no way is intended to be advice for non-qualified operators because of the potential for engine failure and its consequences once the aircraft has left the ground. 

 

Nor am I saying what people have recommended above is wrong. I'm just suggesting you be very careful about modifying fuel, oil, or specification away from what has been extensively tested under load by the manufacturer.

 

When you change the viscosity of fuel, it affects the jetting, particularly the main jets which come into play at full throttle which is usually full load where the engine usually makes the most heat.

 

In racing I have seen many engines fail after someone having a problem with a piston seizure decides to add oil to the fuel for better lubrication. The engine seizes again, so he adds more oil to the mix, it seizes again, quicker this time, and still some add more oil.

 

What is happening in that cycle is that as oil is added to the petrol, the viscosity is lowered and the lower viscosity mix can't squeeze through the jets as quickly. Experts can take care of this by fitting bigger jets, however as I mentioned this is not something for the amateur to play with on an aircraft, where you can't just pull over to the side of the road and make another change.

It is my understanding that it is not the viscosity change that causes the lean seize, but the fact you have reduced the fuel in the fuel oil ratiol, But yes, a change in jetting is necessary to correct that sort of change. As for "experts", if they were an expert, they wouldn't be increasing the amount of 2 stroke oil significantly, because that creates other problems.