90 Octane?

[Roger Lee]

Here is an older article, but an interesting read. It is worth reading.

It will give a good understanding oil oil types and what's in an oil that makes a difference. As you read this pay attention to the part about ZDDP or Zinc

Oil Comparison.pdf

[FlyingMonkey]

Here is an older article, but an interesting read. It is worth reading.

It will give a good understanding oil oil types and what's in an oil that makes a difference. As you read this pay attention to the part about ZDDP or Zinc

 

One non-oil related fact I got from that report, is that with a displacement of 82.6 cubic inches and maximum power output of 100hp, the Rotax 912S/ULS engines have a greater power per cubic inch than the Corvette motor in the first chart. In fact, even at the maximum continuous power of 95hp, the Rotax has 1.14 hp per ci compared to the Corvette's 1.1. The Rotax really is a pretty amazing little engine, especially considering it still uses carbs, fixed timing, and non-variable cams.

[mocfly]

I'm going to put something forward to you as a mechanic. You never trust what comes out of a pilot's mouth.

 

But we pilots are supposed to take whatever a mechanic says at face value?

 

C'mon.

 

I am not trying to engage in a debate over a statement. I am merely trying to understand why CTLSi feels he should change fluids (except gas) if his plane sat idle for 8 weeks. Maybe he knows or has access to information I don't. The reason it's important to me is that sometimes my aircraft could sit for that long.

 

I started by asking to have some sort of data posted to back up an assertion that was made and have not seen any data posted to back up the statements. I am now convinced that the statement is hollow, and I gave no worries.

 

Thank you

 

[FlyingMonkey]

I am not trying to engage in a debate over a statement. I am merely trying to understand why CTLSi feels he should change fluids (except gas) if his plane sat idle for 8 weeks. Maybe he knows or has access to information I don't. The reason it's important to me is that sometimes my aircraft could sit for that long.

 

I think 8 weeks is far too short an interval to be concerned about any of your fluids. If we are talking 8 months, then it might make sense to change the gas, because in that timeframe gasoline does outgas and separate enough to forms some gums and varnish. It probably would not be a problem, but it would give me a warm fuzzy. Oil is probably fine that long, just run it hot enough to boil off any water that has accumulated. After all, even if you change the oil, you have not prevented any water condensation cycles that may have occurred.

 

Because of my surgery, it will probably be 4-5 weeks between my last flight and the next one. I plan to do nothing but a thorough pre-flight before flying.

[mocfly]

Having oil sit for that period is no longer a concern.

 

Andy

Hope your recovery is going well.

[FastEddieB]

Andy,

 

I'd be happy to either fly your plane around the pattern to keep her limber - with you in it if you're up to it!

 

But just starting it up every few weeks and letting it get up to temp should keep the corrosion wolves at bay.

[sandpiper]

I agree with Anticept on the liability issue even though I may be over reacting and, there may be some instances I might forgo the oil change at annual. On the Rotax I would, however check the magnetic plug and split the oil filter. At that point, it's only 3 quarts of oil to complete the job so why not finish it. That way I will have a better feeling about signing off the work.

 

People do shade the truth and sometimes outright lie - pilots and mechanics included. I do believe though that more pilots have lied to me than mechanics. This from having bought and sold about 10 aircraft (claims of no damage history and no corrosion) and having to deal with aircraft with multiple users (it wasn't me that damaged the prop, put the dent in the wing, etc.).

 

Liability is real for mechanics and flight instructors so there is incentive to do the job carefully. I got my LSRM mainly to work on my plane. The one time I did a CT annual as a favor the guy wrecked his plane. Then he claimed it was a left brake pulling that caused it. Brakes that I helped install on a plane that I stated in the log book was safe for continued operation. That gets your attention. Fortunately it was determined that the brakes did not contribute to the accident.

[Anticept]

I'm going to put something forward to you as a mechanic. You never trust what comes out of a pilot's mouth.

 

But we pilots are supposed to take whatever a mechanic says at face value?

 

C'mon.

 

I am not trying to engage in a debate over a statement. I am merely trying to understand why CTLSi feels he should change fluids (except gas) if his plane sat idle for 8 weeks. Maybe he knows or has access to information I don't. The reason it's important to me is that sometimes my aircraft could sit for that long.

 

I started by asking to have some sort of data posted to back up an assertion that was made and have not seen any data posted to back up the statements. I am now convinced that the statement is hollow, and I gave no worries.

 

Thank you

 

Never take anyone's statement at face value. And what i said isn't meant to be a dick to pilots, but honestly, the problem is they are the ones paying, they want to pay as little as possible, and they usually don't know what is going on. Then when something happens, they get mad at the mechanics. Mechanics are treated like garbage by pilots. Big conflict of interest.

 

I just said we always change it at annuals anyways. I made a statement about something that limits oil's life, it wasn't meant to back up any claim, and I stated "two months isn't much to worry about" (post #25). After that, I thought for a bit there you were being one of those "oil change is a scam" people and I really started getting upset and wanted to snap at you (but thought better of it). Sorry about that (:

[Doug G.]

I am my own mechanic and I try my best not to lie to myself. I didn't change oil on my last annual condition inspection. It may be due before the next one. The difficulty I see is that if you don't do your own work you are going to change oil about twice as often as needed if you fly more 50 hours per year, or you are going to extend the oil change intervals.

The other option, I suppose is to have your mechanic change your oil.

If the oil change is entered in the log book along with the filter inspection, and the mag plug inspection, would a mechanic be willing to take that as relieving them of the responsibility?

[Anticept]

I am my own mechanic and I try my best not to lie to myself. I didn't change oil on my last annual condition inspection. It may be due before the next one. The difficulty I see is that if you don't do your own work you are going to change oil about twice as often as needed if you fly more 50 hours per year, or you are going to extend the oil change intervals.

The other option, I suppose is to have your mechanic change your oil.

If the oil change is entered in the log book along with the filter inspection, and the mag plug inspection, would a mechanic be willing to take that as relieving them of the responsibility?

 

If you are a regular, I might be willing to let it go if I were doing the oil changes. Liability and the way pilots treat mechanics is the reason I don't work on planes for the public (unless I'm helping out at a friend's shop). I prefer to work on my own and just rent them out.

[FlyingMonkey]

Andy,

 

I'd be happy to either fly your plane around the pattern to keep her limber - with you in it if you're up to it!

 

But just starting it up every few weeks and letting it get up to temp should keep the corrosion wolves at bay.

 

Thanks Eddie....do you have 5 hours in a CT?

 

I'm planning to make the trip to the airport Saturday to start the engine, if my wife can get it out of the hangar (I'm not allowed to lift or pull that much weight yet).

[FlyingMonkey]

I agree with Anticept on the liability issue even though I may be over reacting and, there may be some instances I might forgo the oil change at annual. On the Rotax I would, however check the magnetic plug and split the oil filter. At that point, it's only 3 quarts of oil to complete the job so why not finish it. That way I will have a better feeling about signing off the work.

 

Seems like the liability would go away with a simple logbook entry stating "oil not changed by request of owner"...and make them sign the entry.

[FastEddieB]

 

 

Thanks Eddie....do you have 5 hours in a CT?

 

 

Nope. Sorry.

 

I could ride along with you as PIC if you're up to it.

[Anticept]

Seems like the liability would go away with a simple logbook entry stating "oil not changed by request of owner"...and make them sign the entry.

 

Customer signatures don't belong in a logbook, and you would not believe to what extent people will go to to get their way. A guy came into my friend's shop for an overhaul exchange for a tecnam. After it was done, the customer demanded his old case back, which was already sent in. He sued the shop owner for it, which the judge laughed at him about because the customer made my friend's case for him. The judge dismissed the case, but the customer then went on a rampage, filing bad reviews with the BBB (which is nothing more than a racketeering operation) and got Tecnam to cancel his service center status.

 

Later, the customer had the balls to come back and try to have his engine looked at, and when he told them no, Tecnam called and tried to ask for a favor. He basically told them all to go to hell.

 

Another time, a customer brought in their Taylorcraft which needed some major work. One thing was the tailwheel tire, which was on backorder for months. Customer comes in with a different TW assembly and tries to get my friend to change it out, and the local FSDO refused to do a field approval. The customer didn't want to pay a DER to make the STC for it. So he comes up with the idea of injecting medical grade vulcanizing rubber into the tire and fixing the flat spot that way. Friend flat out refuses, and I told my friend you better get this guy out of your shop ASAP. My friend gave him an unairworthy signoff and got him out the door. Later, the local FSDO inspectors walk in asking questions about the plane, and it would seem the customer had filed a complaint and tried to tell the FSDO that my friend was running a shoddy operation, that he felt his plane wasn't safe, etc. My friend told them to have a look at his logbook, he gave it an unairworthy signoff. They ended their questioning and left.

 

There's a LOT more stories that I have, which has made me cynical and jaded about other pilots. That's why I'm so cautious and defensive. Unless I know you well and trust you, you will get your oil changed. It's a common practice and I must have VERY good reason not to.

[sandpiper]

I am my own mechanic and I try my best not to lie to myself. I didn't change oil on my last annual condition inspection. It may be due before the next one. The difficulty I see is that if you don't do your own work you are going to change oil about twice as often as needed if you fly more 50 hours per year, or you are going to extend the oil change intervals.

The other option, I suppose is to have your mechanic change your oil.

If the oil change is entered in the log book along with the filter inspection, and the mag plug inspection, would a mechanic be willing to take that as relieving them of the responsibility?

 

At annual,at the very least I am going to do the mag plug and split the filter. You don't know what has happened in the 5 or so hours since it was done. You may trust the guy not to sue you but what about his estate? It's very unfortunate we have to worry about such things but, we do.

 

Neighbors son in law sued him for his wife's injury due to engine failure not due to his negligence. My son in law and his front seat passenger survived a mid air but the two back seat passengers died because the back seat came out. Their estate sued Cessna saying if the plane was built right the seat would not have come out and they would have lived. Never mind that the other planes prop is what caused the seat to come out. Cessna prevailed but it cost them.

[Doug G.]

In my case I only work on my own plane and I trust the ability and honesty of both the pilot and mechanic.

[sandpiper]

In my case I only work on my own plane and I trust the ability and honesty of both the pilot and mechanic.

 

You're one up on me, at least some of the time!

[FredG]

Anticept, just getting back to this. I think you are incorrect about separation of gasolines that differ in octane. Your example is not analogous, cream separates from milk because one is lipid and one is aqueous. Getting them to stay together is the hard part.

 

Two similar organic solvents (two gasolines differing only by octane value) will be fully miscible in each other (regardless of the proportions). They will, in essence, dissolve fully into each other and create a homogeneous mixture that will not separate. If you find evidence to the contrary, I would be very interested in seeing it.

 

Fred

[Roger Lee]

What happened to the 90 octane post?

[Anticept]

Anticept, just getting back to this. I think you are incorrect about separation of gasolines that differ in octane. Your example is not analogous, cream separates from milk because one is lipid and one is aqueous. Getting them to stay together is the hard part.

 

Two similar organic solvents (two gasolines differing only by octane value) will be fully miscible in each other (regardless of the proportions). They will, in essence, dissolve fully into each other and create a homogeneous mixture that will not separate. If you find evidence to the contrary, I would be very interested in seeing it.

 

Fred

 

Hi Fred!

 

I had voiced that I doubt it's an issue, but I don't trust it in aircraft. You're right on the milk thing though!

[Doug G.]

A man who is his own lawyer has a fool for a client

 

No more than it would apply to a lawyer being his own client. I know more about my plane than nearly any A&P you might find. Most of them don't know Rotax.

Does that also apply to being your own A&P mechanic?

[Anticept]

Hi Doug!

 

My personal thought is that if you only use it for yourself, i wouldn't worry about it. Since mine is also rented, i prefer to have someone else do an inspection from time to time to make sure the I's are dotted and Ts are crossed.

[Doug G.]

Agreed!