X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 30 Jan 2012 10:52:46 -0500 Message-ID: X-Original-Return-Path: Received: from nm30-vm2.bullet.mail.ne1.yahoo.com ([98.138.91.130] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with SMTP id 5369927 for lml@lancaironline.net; Mon, 30 Jan 2012 09:13:39 -0500 Received-SPF: none receiver=logan.com; client-ip=98.138.91.130; envelope-from=casey.gary@yahoo.com Received: from [98.138.90.49] by nm30.bullet.mail.ne1.yahoo.com with NNFMP; 30 Jan 2012 14:13:04 -0000 Received: from [98.138.88.239] by tm2.bullet.mail.ne1.yahoo.com with NNFMP; 30 Jan 2012 14:13:04 -0000 Received: from [127.0.0.1] by omp1039.mail.ne1.yahoo.com with NNFMP; 30 Jan 2012 14:13:04 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 160827.71673.bm@omp1039.mail.ne1.yahoo.com Received: (qmail 51358 invoked by uid 60001); 30 Jan 2012 14:13:04 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=v9N0P1md4FrW4kLhwP8GHIzfcpCS9BLPlhQSAOqS+HiM4uUSErp0qJhUVxooASzNdVWqYW/W/hFqmqJUUOLATgiSMHd9SM+O//yPRd5X61n/b3KA4ep1IN2dTGR1/35JDPO9Elzd/s38aj0fTigdEIWZpwMsacKsSql+JXDU00w=; X-YMail-OSG: VOe9LrMVM1km3Pa8iNIKDKaqdDIBsfDFoKn6F_4glX3UQ0G JWQpKz0z1Ge0ZM8EX8eDhwjMgoe_ZkoRnV0fH4tuOuz6AyRvmdLA0KqZJzQx I5AEWLwLxwbdAd5XobUSxA8wF3HIKQKVlKNMMbivv6hW1ZP72TK0OYUq.c5x klMb3M_Cfl3iN7G2YKCJIajgLsIwq0vTfr0Fb3H09YWB.3I6UEq_5KBFZ6cD ntLQrFBiM_obsTJrSBeZYgixS9JLsqyqxIoJIMW1P_BRmoC83y4wtWZ7IIo9 BlihfJkdJ77RuE1_sIYiUbl9er8Qmss889kmTwwVSROTM2ANIApcVwco5kq5 rGOmzogpNvw3MkKdCXCee1bGpxNZ1CNlXrEN7jOTt_aFdJoumb1KSHzYtYPo c3f0vAGM4GIY9iGaHEBqlap0wmNASplGaWltWInj1zua0YoWkUIL2cBDAlQ- - Received: from [71.208.88.15] by web125602.mail.ne1.yahoo.com via HTTP; Mon, 30 Jan 2012 06:13:03 PST X-Mailer: YahooMailWebService/0.8.116.331537 References: X-Original-Message-ID: <1327932783.19649.YahooMailNeo@web125602.mail.ne1.yahoo.com> X-Original-Date: Mon, 30 Jan 2012 06:13:03 -0800 (PST) From: Gary Casey Reply-To: Gary Casey Subject: Re: Lycoming exhaust valve questions X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-1088529044-438000761-1327932783=:19649" ---1088529044-438000761-1327932783=:19649 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Swaid,=0ASorry about the name misspelling - now that I think of it I used t= o know someone named Swain.... =A0One problem with these lists is that it i= s tempting to abbreviate posts to save time. =A0Sometimes a longer answer i= s better, and this is no exception - so I recommend that anyone not particu= larly interested in this topic hit the delete button now :-). =A0As for oil= change intervals, there is no one factor that determines the "best" oil ch= ange interval, even if there is a single "best" interval. =A0A long time ag= o, far, far away (in Detroit) I watched with interest some testing done at = GM. =A0It was shortly after the change to lead-free fuel and the question c= ame up about oil change intervals, which I think at the time were recommend= ed at 2,000 miles. =A0We had lots of company cars that were typically drive= n for 6 months to a year and then sold. =A0The "policy" was that we never s= erviced any of them. =A0Should we have? =A0So we took a rather large fleet = (some competitor's, too) and drove them with various oil change intervals. =A0We= found that there was very little difference between 2,000 mile and 50,000 = mile intervals. =A0If you looked at the statistics, you might barely detect= a slightly higher incidence of engine trouble with the higher intervals, b= ut just barely.=0A=0AThen I worked on a project with oil experts from an oi= l company. =A0Their opinion was that you could look at oil and with a littl= e practice see that it was ready for a change. =A0Lead is gray, carbon is b= lack and water is...well, sludgy. =A0 Their point was that modern oil filte= rs do a pretty good job and oil by itself doesn't "go bad", it just gets co= ntaminated. =A0Are there invisible contaminants? =A0Maybe, but what are the= y and where did they come from? =A0Then there is the simple logic that ther= e is no such thing as "good" and "bad" oil. =A0The oil gets progressively m= ore contaminated, so it never goes over the cliff and suddenly becomes bad.= =A0There was an excellent post that stated that the multi-viscosity additi= ve (VI improver) broke down with use (actually, shear rate and temperature)= and gradually became thinner. =A0True, but at the same time the lighter en= ds evaporate, so does the oil viscosity go up or down with use? =A0It can d= o either.=0A=0AAnd there is the history of aircraft engines. =A0Oil change = intervals have been recommended at 50 hours for many, many years. =A0I reme= mber it being 25 hours with no filter and 50 hours with a filter. =A0What h= as happened since? =A0First, the oil itself has a much better additive pack= age that reduces "aging." =A0Multiviscosity oils reduce the demand for chan= ging oil on account of weather. =A0Synthetic oils have a much more stable v= iscosity. =A0Oil coolers have thermostats to keep oil warm in the winter. = =A0Piston rings and cylinder materials and finishes are better than before.= =A0Lead content, one of the bigger contaminants, hasn't changed much, but = with LOP operation much less of it finds its way to the oil. =A0So in summa= ry, many conditions have changed and almost all would indicate a longer oil= change interval - but the recommendations haven't changed. =A0And why woul= d the OEM's increase the recommendation? They have absolutely no incentive = to do that, as it doesn't save them any money and can only cost litigation.=0A=0AThen there = is cost. =A0I'll admit I have never paid for an oil change, but I would gue= ss it would cost about $200 most places. =A0Just the oil and filter cost ov= er $50. =A0So if you change the oil and filter every 25 hours, at 2,000 hou= rs you have paid about $16,000 for oil changes! =A0That's almost enough to = overhaul the enigne. =A0Let's say you get aggressive and change the oil eve= ry 75 hours, 50% longer than "recommended." =A0At 2,000 hours you have save= d $12,000 on oil changes compared to the 25-hour changes. =A0How much longe= r would the engine have lasted with frequent oil changes? =A0100 hours? =A0= 200? =A0Even 500? =A0You can see where this is going. =A0I have heard the c= omment "oil is cheaper than engines, so I'll change it more often." =A0Is i= t? =A0How much oil do you have to buy to increase the life of the engine an= d by how much?=0A=0AAnd do the manufacturers know what they are talking abo= ut? =A0Sure, the engineers - and their lawyers - are smart guys. =A0What is= published comes from the lawyers, not the engineers. =A0I still maintain t= hat if an engine is "intelligently" operated it will run a long time with e= xtended oil change intervals. =A0How do you run an engine with intelligence= ? =A0Don't shut it off until the oil has been "cooked" enough to drive out = the water. =A0Don't store it for more than a couple of weeks. =A0Don't keep= it warm in the winter. =A0Don't get the CHT's much over 400 and cooler is = better. =A0That's about it. =A0Shock cooling - never mind, that's another t= opic. =A0So when do I change oil? =A0I target 50 hours (see, I'm a coward t= hat is unwilling to follow his own advice!), but that's when I start thinki= ng about it. =A0If I'm on a trip I certainly won't change it until I get ho= me. =A0I'll probably wait until the oil is burned down a bit - no point in = changing oil I just put in. =A0So the bottom line is that the part-synthetic oil will get changed neve= r sooner than 50 hours and hardly ever later than 75. =A0And the oil is alm= ost never changed at annual inspection time, as that never seems to coincid= e with an oil change interval. =A0False economy? =A0Don't know for sure - n= obody does - but I've run multiple engines like that well over their TBO. = =A0I'm satisfied.=0A=0AI've already taken far too much of everyone's readin= g time and for that I apologize. =A0=0AGary=0A=0AGary,=0AMy name is=A0=A0= =A0=A0=A0=A0=A0 Swaid=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 not=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0Swain.=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Yo= u have some interesting procedures for the care and feeding of your engine.= What data do you have to back up extending your oil change intervals? Is i= t that you just don't want to spend the money?=0AAlso all contaminates in o= il=A0are not black. There is also a calendar interval for oil change regard= less of operating hours, it's to prevent corrosion inside the engine due to= condensation.=0A=A0Also there is more to a compression test than just the = number. There is a real neat place to get the right information on operatin= g and maintenance of your engine. It's called the manufacturer. They have a= vested interest in helping you get the best service from=A0their product. = Believe it or not they really know what they are talking about.=0A=A0Best o= f luck with your TBO,=0ASwaid Rahn=0A ---1088529044-438000761-1327932783=:19649 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Swaid,
Sorry about the name misspelling - now that I thi= nk of it I used to know someone named Swain....  One problem with thes= e lists is that it is tempting to abbreviate posts to save time.  Some= times a longer answer is better, and this is no exception - so I recommend = that anyone not particularly interested in this topic hit the delete button now :-). &= nbsp;As for oil change intervals, there is no one factor that determines th= e "best" oil change interval, even if there is a single "best" interval. &n= bsp;A long time ago, far, far away (in Detroit) I watched with interest som= e testing done at GM.  It was shortly after the change to lead-free fu= el and the question came up about oil change intervals, which I think at th= e time were recommended at 2,000 miles.  We had lots of company cars t= hat were typically driven for 6 months to a year and then sold.  The "= policy" was that we never serviced any of them.  Should we have?  = ;So we took a rather large fleet (some competitor's, too) and drove them wi= th various oil change intervals.  We found that there was very little = difference between 2,000 mile and 50,000 mile intervals.  If you looke= d at the statistics, you might barely detect a slightly higher incidence of engine trouble with the higher intervals, but just barely.

Then I worked on a project with oil experts from an = oil company.  Their opinion was that you could look at oil and with a = little practice see that it was ready for a change.  Lead is gray, car= bon is black and water is...well, sludgy.   Their point was that moder= n oil filters do a pretty good job and oil by itself doesn't "go bad", it j= ust gets contaminated.  Are there invisible contaminants?  Maybe,= but what are they and where did they come from?  Then there is the si= mple logic that there is no such thing as "good" and "bad" oil.  The o= il gets progressively more contaminated, so it never goes over the cliff an= d suddenly becomes bad.  There was an excellent post that stated that = the multi-viscosity additive (VI improver) broke down with use (actually, s= hear rate and temperature) and gradually became thinner.  True, but at the same time the lighter ends evaporate, so does the oil viscosity= go up or down with use?  It can do either.

A= nd there is the history of aircraft engines.  Oil change intervals hav= e been recommended at 50 hours for many, many years.  I remember it be= ing 25 hours with no filter and 50 hours with a filter.  What has happ= ened since?  First, the oil itself has a much better additive package = that reduces "aging."  Multiviscosity oils reduce the demand for chang= ing oil on account of weather.  Synthetic oils have a much more stable= viscosity.  Oil coolers have thermostats to keep oil warm in the wint= er.  Piston rings and cylinder materials and finishes are better than = before.  Lead content, one of the bigger contaminants, hasn't changed = much, but with LOP operation much less of it finds its way to the oil. &nbs= p;So in summary, many conditions have changed and almost all would indicate a longer oil change interval - but the recommendations haven't ch= anged.  And why would the OEM's increase the recommendation? They have= absolutely no incentive to do that, as it doesn't save them any money and = can only cost litigation.

Then there is cost. &nbs= p;I'll admit I have never paid for an oil change, but I would guess it woul= d cost about $200 most places.  Just the oil and filter cost over $50.=  So if you change the oil and filter every 25 hours, at 2,000 hours y= ou have paid about $16,000 for oil changes!  That's almost enough to o= verhaul the enigne.  Let's say you get aggressive and change the oil e= very 75 hours, 50% longer than "recommended."  At 2,000 hours you have= saved $12,000 on oil changes compared to the 25-hour changes.  How mu= ch longer would the engine have lasted with frequent oil changes?  100= hours?  200?  Even 500?  You can see where this is going.  I have heard the comment "oil is cheaper than engines, so I'l= l change it more often."  Is it?  How much oil do you have to buy= to increase the life of the engine and by how much?

And do the manufacturers know what they are talking about?  Sure, t= he engineers - and their lawyers - are smart guys.  What is published = comes from the lawyers, not the engineers.  I still maintain that if a= n engine is "intelligently" operated it will run a long time with extended = oil change intervals.  How do you run an engine with intelligence? &nb= sp;Don't shut it off until the oil has been "cooked" enough to drive out th= e water.  Don't store it for more than a couple of weeks.  Don't = keep it warm in the winter.  Don't get the CHT's much over 400 and coo= ler is better.  That's about it.  Shock cooling - never mind, tha= t's another topic.  So when do I change oil?  I target 50 hours (see, I'm a coward that is unwilling to follow his own advice!), but= that's when I start thinking about it.  If I'm on a trip I certainly = won't change it until I get home.  I'll probably wait until the oil is= burned down a bit - no point in changing oil I just put in.  So the b= ottom line is that the part-synthetic oil will get changed never sooner tha= n 50 hours and hardly ever later than 75.  And the oil is almost never= changed at annual inspection time, as that never seems to coincide with an= oil change interval.  False economy?  Don't know for sure - nobo= dy does - but I've run multiple engines like that well over their TBO. &nbs= p;I'm satisfied.

I've already taken far too much o= f everyone's reading time and for that I apologize.  
Gary

Gary,
My name is    =     Swaid        &nb= sp;    not        &n= bsp;       Swain.    = ;       You have some interesting procedures = for the care and feeding of your engine. What data do you have to back up e= xtending your oil change intervals? Is it that you just don't want to spend= the money?
Also all contaminates in oil are not black. Ther= e is also a calendar interval for oil change regardless of operating hours,= it's to prevent corrosion inside the engine due to condensation.
 Also there is more to a compression test than just the number. There= is a real neat place to get the right information on operating and mainten= ance of your engine. It's called the manufacturer. They have a vested interest in helping you get the best service from their produc= t. Believe it or not they really know what they are talking about.
 Best of luck with your TBO,
Swaid Rahn

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