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Ben2k9

100LL questions

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Based on how my plane will be used, 100LL may have to be used from time to time unfortunately.  I’ve done some reading on the forum and have seen Decalin mentioned. When should Decalin be used?  Only when tank is 100% avgas?  

Oil changes: I’ve looked in the Rotax maintenance manual and want to be sure I understand what I’m seeing.  If I read it correctly, oil changes are normally every 100 hrs.  If 100LL is used 30%, then this goes to 50hrs.  I didn’t see it in the manual but have been told and read somewhere that using 100LL more than 50% requires an oil change every 25 hours.  Am I correct on all the above assumptions?

its a shame most airports are so bogged down with red tape to allow swift or mogas.  It doesn’t look either will be coming to any airports around me anytime soon.  

 

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My understanding is , every 50 hours if using Mogas/UL94 and every 25 hours  when using 100LL more than 30% of time.

 I am actually lucky in that I have 3 airports within 20 minutes flight with fuel other than 100Ll , one with Mogas 91 and  2 with UL94.

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Warmi is correct on the intervals and percentages.  I think Decalin is added at 1/2oz per ten gallons.  So if you put five gallons of 100LL in the tank, add 1/4oz, even if it’s mixed with Mogas.

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Technically 25 hrs for leaded use and 50 hrs for unleaded are the recommended oil change intervals as per the Rotax SI. The required intervals are 50/100 hrs.

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3 hours ago, FlyingMonkey said:

Warmi is correct on the intervals and percentages.  I think Decalin is added at 1/2oz per ten gallons.  So if you put five gallons of 100LL in the tank, add 1/4oz, even if it’s mixed with Mogas.

Does adding Decalin allow you to go 50hrs if even at 30% avgas?  Or is this just for other benefits 

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The Decalin helps with scavenging the lead, but the oil change requirements are still the same. I don't think Rotax approves Decalin as an additive, but use in the field indicates that it does help with the lead.

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If you have seen the bottom of an oil tank on a Rotax that has used 100LL you would do your best to avoid using it.

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(As dictated by Hubby, who is a certified Rotax repairman)

Decalin is not approved by Rotax as a fuel additive.  It is not tested.  Its efficacy is questionable.  It is a lead scavenger.  Rather than spending money on an expensive additive, just change your oil.  Service Instruction SI-912-016 includes information about using low lead.  If you are using 100LL more than 30% of the time, you should change the oil and filter every 50 hours.  If you are using 100LL most of the time change the oil and filter every 25 hours and also clean out the oil tank when you change the oil because that's where the oil settles.  And you should check the spark plugs more often. http://docusearch.flyrotax.com/files/pdf/d06038.pdf

If you are flying a SLSA you are pretty much bound by what the manufacturer says.  If it is an experimental, you can do whatever you want.

Edited by AuntPeggy
Link to SI

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There are several things Rotax doesn’t recommend I writing and that’s only because they haven’t spent the money to test for a thousand hours. That doesn’t mean it doesn’t work or that they condone it. Decal in does work if you read how it works chemically. It isn’t a cure all against lead, but nothing is, but it makes a difference.  1/2 ounce per 10 gal. It isn’t expensive when you weigh the consequences for not using it when using 100LL all the time. Most of us get stuck using 100LL when we trave. Rotax specs the oil tank cleaning every 200 hours as spelled out on the maint. checklist. When you change the oil the filter goes to.

People use up to 23% ethanol to and even though Rotax only has 10% in writing high ethanol use has not hurt a thing. It is all Rotax spent the money on to test.

the oil is like the blood in a person. Disease it or neglect it and you die early. The electrical system is like your human nervous system. Damage or neglect it and it ceases to function properly. 

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Wow, lighten up a little maybe?  It's an analogy, no analogy is perfect, or it would be a tautology.  The analogy Roger made was:

Quote

Disease it or neglect it and you die early.

 

(human blood does get changed out through cellular replenishment, just not all at one time... :)

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You missed the point Fred.

Preventative maint. and don’t penny pinch is the analogy.

Your life and a loved one or friend may depend on how good a doctor you are or how neglectful a patient (owner) you are.  

BUT,

You give your plane a physical every year. :eyebrow-1057:

P.s.

People do go to the Doc every so many hours or die. Dialysis is like taking the lead out without  Decalin and that may be every week or two.. :giggle-3307:

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You guys are right.  Rigor, accuracy, and clarity of communication are irrelevant on this site.  Not sure what I was thinking.

  • Upvote 1

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You think every statement on here has to be 100% verifiably accurate, facts only with no opinions, analogies, jokes, or other statements of non-fact?  This is a discussion forum, not an engineering class.  I agree, I don't know what you were thinking either.

Welcome to the internet, by the way.  Prepare to be very frustrated.

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That's always the issue with black and white text. No emotions, facial expressions and voice inflection. So people take things the wrong way. Plus people that have never met do not know the individual. I always joke and NEVER get upset. But I do like to have fun with people who do get upset. :eyebrow-1057::rolleyes:

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23 minutes ago, Roger Lee said:

But I do like to have fun with people who do get upset. :eyebrow-1057::rolleyes:

Anybody in particular?:D

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Confucius say:

I'm an equal opportunity teaser.  :giggle-3307:

Life's too short not to make other people smile. Was I a serious type when I first met you and Andy? :bow_to_each_other-968:  If someones a perpetual grump :bad_day-3329:  they aren't going to like me and that's okay. Too many nice and fun people in the world to let one influence your life. :hi-1082:

Happy Camper til the end..

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It's all good.  I know I have a tendency to sound very pointed and abrasive when I'm countering posts I disagree with, like I did to Fred's post above.  But I'm really not getting angy about it, I just have a perverse need to poke at things.  I should probably use smileys more...

I hope Fred and others realize that and don't take it too personally.  I have had a lot of interactions with Fred on here and think he's a fine person and pilot.

I can count on two fingers the folks on this forum that really annoyed me, and neither of them is here anymore.

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4 hours ago, FlyingMonkey said:

I can count on two fingers the folks on this forum that really annoyed me, and neither of them is here anymore.

I'll have to work harder.

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7 hours ago, Tom Baker said:

I'll have to work harder.

Just tell him his airplane is prettier than he is.

It's true but it's like kicking a dog while they are down.

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8 hours ago, Roger Lee said:

And I can't wait see Andy and Bill again.:eyebrow-1057::laughter-3293:

Flattery will get you nowhere.

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