X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 30 Jan 2012 12:09:44 -0500 Message-ID: X-Original-Return-Path: Received: from mail-lpp01m010-f52.google.com ([209.85.215.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTPS id 5370100 for lml@lancaironline.net; Mon, 30 Jan 2012 11:07:11 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.52; envelope-from=indigoaviation@gmail.com Received: by lagy4 with SMTP id y4so1331892lag.25 for ; Mon, 30 Jan 2012 08:06:34 -0800 (PST) MIME-Version: 1.0 Received: by 10.152.112.132 with SMTP id iq4mr9147528lab.28.1327939594710; Mon, 30 Jan 2012 08:06:34 -0800 (PST) Received: by 10.112.45.33 with HTTP; Mon, 30 Jan 2012 08:06:34 -0800 (PST) In-Reply-To: References: X-Original-Date: Mon, 30 Jan 2012 11:06:34 -0500 X-Original-Message-ID: Subject: Re: [LML] Re: Lycoming exhaust valve questions From: swaid rahn X-Original-To: Lancair Mailing List Content-Type: multipart/alternative; boundary=f46d0408d673d36f2404b7c107d1 --f46d0408d673d36f2404b7c107d1 Content-Type: text/plain; charset=ISO-8859-1 Gary, Thank you for the time you took in writing this article. I don't think there is anything there I can or should disagree with. By the way I am not here to find arguments or disputes only to further my aviation education. Thanks again for your insight. Swaid On Mon, Jan 30, 2012 at 10:52 AM, Gary Casey wrote: > Swaid, > Sorry about the name misspelling - now that I think of it I used to know > someone named Swain.... One problem with these lists is that it is > tempting to abbreviate posts to save time. Sometimes 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 :-). As > for oil change intervals, there is no one factor that determines the "best" > oil change interval, even if there is a single "best" interval. A long > time ago, far, far away (in Detroit) I watched with interest some testing > done at GM. It was shortly after the change to lead-free fuel and the > question came up about oil change intervals, which I think at the time were > recommended at 2,000 miles. We had lots of company cars that 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 with various oil change > intervals. We found that there was very little difference between 2,000 > mile and 50,000 mile intervals. If you looked 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, carbon is black and water > is...well, sludgy. Their point was that modern oil filters do a pretty > good job and oil by itself doesn't "go bad", it just gets contaminated. > Are there invisible contaminants? Maybe, but what are they and where did > they come from? Then there is the simple logic that there is no such thing > as "good" and "bad" oil. The oil gets progressively more contaminated, so > it never goes over the cliff and suddenly becomes bad. There was an > excellent post that stated that the multi-viscosity additive (VI improver) > broke down with use (actually, shear 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. > > And there is the history of aircraft engines. Oil change intervals have > been recommended at 50 hours for many, many years. I remember it being 25 > hours with no filter and 50 hours with a filter. What has happened since? > First, the oil itself has a much better additive package that reduces > "aging." Multiviscosity oils reduce the demand for changing oil on account > of weather. Synthetic oils have a much more stable viscosity. Oil coolers > have thermostats to keep oil warm in the winter. 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. So in summary, many conditions have > changed and almost all would indicate a longer oil change interval - but > the recommendations haven't changed. 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. I'll admit I have never paid for an oil change, but I > would guess it would 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 you have paid about $16,000 for oil changes! That's almost > enough to overhaul the enigne. Let's say you get aggressive and change the > oil every 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 much > 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'll 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, the > engineers - and their lawyers - are smart guys. What is published comes > from the lawyers, not the engineers. I still maintain that if an engine is > "intelligently" operated it will run a long time with extended oil change > intervals. How do you run an engine with intelligence? Don't shut it off > until the oil has been "cooked" enough to drive out the 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 cooler is better. That's about it. > Shock cooling - never mind, that'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 > bottom line is that the part-synthetic oil will get changed never sooner > than 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 - nobody does - > but I've run multiple engines like that well over their TBO. I'm satisfied. > > I've already taken far too much of everyone's reading time and for that I > apologize. > Gary > > Gary, > My name is Swaid not Swain. > You 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 it that you just don't want to spend the money? > Also all contaminates in oil are not black. There 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 maintenance > of your engine. It's called the manufacturer. They have a vested interest > in helping you get the best service from their product. Believe it or not > they really know what they are talking about. > Best of luck with your TBO, > Swaid Rahn > > -- Swaid L. Rahn Indigo Aviation, Inc. 940 Mock Road Springfield, Ga. 31329 Cell 912.655.0966 --f46d0408d673d36f2404b7c107d1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Gary,
Thank you for the time you took in writing this article. I don't t= hink there is anything there I can or should disagree with. By the way I am= not here to find arguments or disputes only to further my aviation educati= on. Thanks again for your insight.
Swaid

On Mon, Jan 30, 2012 at 10:52 AM, Gary Casey <casey.gary@yahoo= .com> wrote:
Swaid,
Sorry about the name misspelling - now that I think of it I used to kn= ow someone named Swain.... =A0One problem with these lists is that it is te= mpting to abbreviate posts to save time. =A0Sometimes a longer answer is be= tter, and this is no exception - so I recommend that anyone not particularl= y interested in this topic hit the delete button now :-). =A0As for oil cha= nge intervals, there is no one factor that determines the "best" = oil change interval, even if there is a single "best" interval. = =A0A long time ago, far, far away (in Detroit) I watched with interest some= testing done at GM. =A0It was shortly after the change to lead-free fuel a= nd the question came up about oil change intervals, which I think at the ti= me were recommended at 2,000 miles. =A0We had lots of company cars that wer= e typically driven for 6 months to a year and then sold. =A0The "polic= y" was that we never serviced 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 diffe= rence 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, but just barely.

Then I worked on a project with oil experts from an oil company. =A0Th= eir opinion was that you could look at oil and with a little practice see t= hat it was ready for a change. =A0Lead is gray, carbon is black and water i= s...well, sludgy. =A0 Their point was that modern oil filters do a pretty g= ood job and oil by itself doesn't "go bad", it just gets cont= aminated. =A0Are there invisible contaminants? =A0Maybe, but what are they = and where did they come from? =A0Then there is the simple logic that there = is no such thing as "good" and "bad" oil. =A0The oil ge= ts progressively more contaminated, so it never goes over the cliff and sud= denly becomes bad. =A0There was an excellent post that stated that the mult= i-viscosity additive (VI improver) broke down with use (actually, shear rat= e and temperature) and gradually became thinner. =A0True, but at the same t= ime the lighter ends evaporate, so does the oil viscosity go up or down wit= h use? =A0It can do either.

And there is the history of aircraft engines. =A0Oil change intervals = have been recommended at 50 hours for many, many years. =A0I remember it be= ing 25 hours with no filter and 50 hours with a filter. =A0What has happene= d since? =A0First, the oil itself has a much better additive package that r= educes "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 s= ummary, many conditions have changed and almost all would indicate a longer= oil change interval - but the recommendations haven't changed. =A0And = why would the OEM's increase the recommendation? They have absolutely n= o incentive to do that, as it doesn't save them any money and can only = cost litigation.

Then there is cost. =A0I'll admit I have never paid for an oil cha= nge, but I would guess it would cost about $200 most places. =A0Just the oi= l and filter cost over $50. =A0So if you change the oil and filter every 25= hours, at 2,000 hours you have paid about $16,000 for oil changes! =A0That= 's almost enough to overhaul the enigne. =A0Let's say you get aggre= ssive and change the oil every 75 hours, 50% longer than "recommended.= " =A0At 2,000 hours you have saved $12,000 on oil changes compared to = the 25-hour changes. =A0How much longer would the engine have lasted with f= requent oil changes? =A0100 hours? =A0200? =A0Even 500? =A0You can see wher= e this is going. =A0I have heard the comment "oil is cheaper than engi= nes, so I'll change it more often." =A0Is it? =A0How much oil do y= ou have to buy to increase the life of the engine and by how much?

And do the manufacturers know what they are talking about? =A0Sure, th= e engineers - and their lawyers - are smart guys. =A0What is published come= s from the lawyers, not the engineers. =A0I still maintain that if an engin= e is "intelligently" operated it will run a long time with extend= ed oil change intervals. =A0How do you run an engine with intelligence? =A0= Don't shut it off until the oil has been "cooked" enough to d= rive 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 muc= h over 400 and cooler is better. =A0That's about it. =A0Shock cooling -= never mind, that's another topic. =A0So when do I change oil? =A0I tar= get 50 hours (see, I'm a coward that is unwilling to follow his own adv= ice!), but that's when I start thinking about it. =A0If I'm on a tr= ip I certainly won't change it until I get home. =A0I'll probably w= ait until the oil is burned down a bit - no point in changing oil I just pu= t in. =A0So the bottom line is that the part-synthetic oil will get changed= never sooner than 50 hours and hardly ever later than 75. =A0And the oil i= s almost never changed at annual inspection time, as that never seems to co= incide with an oil change interval. =A0False economy? =A0Don't know for= sure - nobody does - but I've run multiple engines like that well over= their TBO. =A0I'm satisfied.

I've already taken far too much of everyone's reading time and= for that I apologize. =A0
Gary

Gary,
My 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 You have some interesting procedures for the care and fe= eding of your engine. What data do you have to back up extending your oil c= hange intervals? Is it that you just don't want to spend the money?
Also all contaminates in oil=A0are not black. There is also a calendar= interval for oil change regardless of operating hours, it's to prevent= corrosion inside the engine due to condensation.
=A0Also there is more to a compression test than just the number. Ther= e is a real neat place to get the right information on operating and mainte= nance 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.
=A0Best of luck with your TBO,
Swaid Rahn




--
Swaid L. RahnIndigo Aviation, Inc.
940 Mock Road
Springfield, Ga. 31329
Cell = 912.655.0966


--f46d0408d673d36f2404b7c107d1--