Notes on Corvair flight engine oils.


A friend of ours sent in a question on oils, which was sparked by reading an internet discussion group story about “experimenting” with oils for Corvair flight engines. It is a free world and people can do as they wish, but to my perspective, the subject of oil for Corvair flight engines is very simple.

Below is a picture of Shell Rotella T 15W-40 oil. This is the oil that we suggest people use in their flight engines. I am going to guess that 90 percent of the hours logged on Corvairs last year were done with this oil. We have been using it since 1996, and I have had a very long time to examine the long-term wear characteristics, it’s ability to withstand heat, its compatibility with 100LL, and it anti corrosion characteristics. This oil is a winner on all fronts. Add to this, that it is available at any auto parts store or Wal-Mart and it is fairly cheap, and I begin to ask myself why anyone would be looking for another oil.

In the manual, I try to teach my saying, “It isn’t the probability of being right, it is the cost of being wrong.”  Oil example: Years ago, Woody Harris, our west coast guy thinks that Aeroshell is airplane oil, and may be better for our “Airplane” application. He is pretty sure this has good promise. Here was the cost of being wrong in that instance: His engine ate the new cam and lifters in 1 hour of running on Aeroshell. This is because the element we care about, Zinc Phosphate is about 800 PPM in Rotella, about 200 PPM in normal oil, and ZERO PPM in Aeroshell.

Let’s say you have always used imaginary Dyno-syn 10-40 in every car you have had in the last 10 years with great luck. It doesn’t count: Modern cars have roller cams, and don’t need zinc. Lets say you have used Unicorn 20w-50 in all your cars for the last 30 years, and all your cars were Corvairs. It doesn’t count: You didn’t run your cars on leaded fuel, and this matters. I could go on like this for a while, but you get the point. Any recommendation has to be just about what we do with Corvairs.

OK, what about synthetic? OK, why use it? “It has good heat resistance”. So does Rotella, which you can actually run at 300 F without hurting it. If your engine runs hotter than this, lack of synthetic isn’t your problem. OK, “I want to go 100 hours between oil changes and having to look in the cowl.” If this is a goal of yours,  walk over to your book shelf, take my manual down, put it in an envelope, write “I want a refund because I couldn’t learn anything from WW “ on the outside, and mail it back to me. Oil changes are a very good inspection point on aircraft engines, and a tremendous amount of small issues are caught and corrected before they become a problem.  Your engine is your personal masterpiece. You should be tempted to pull the cowl off and just marvel at it for no reason.  You should drag passers-by at the airport into your hangar and proudly say “LOOK! I built That!” With an arm gesture that magicians use as they say “TAA-DAA!”

25 hours is a reasonable goal on inspections. You could probably run 50 hours on Rotella between changes but learn this phrase that every A&P worth a damn has tattooed on heart: “Gas and oil are the cheapest things you ever put into an engine.” Here is the WW corollary: “Gas and oil are also the easiest ‘parts’ to install.”

 Lets say a real cheap sob likes to lean his engine beyond peak egt because he read an article written by some d-bag in Flying magazine, and this article sounded great because it provided techno-mumbo-jumbo, (complete with graphs!) that justified Mr cheapskates inner need to avoid spending a dime. At the end of the year, he gets out a calculator and finds out he had a 22% better time than other pilots because he “saved” $1,200 by leaning his engine and only changing the Kmart house brand oil once every 100 hours.  Problem: He does a differential compression test and finds out that he detonated his pistons to death and scoured his cylinder walls, You guessed it, he is out $1,200! net savings: ZERO.  But the big one: How much extra time did it take me to change the oil four more times and pump another 200 gallons of gas in my plane? Think that Mr. Cheapskate can overhaul his engine that fast?

Do you want to try some “super special, secret ingredient, made by Amish people who don’t use combustion  engines, purple/green/ yellow, Brad-Penn, Brad Pitt/Sean Penn oil?” Go back to question #1: What ‘problem’ are you ‘solving?’ Read my story about The Panther engine again. It just had a perfect break in run and test period, it has perfect compression, it doesn’t run hot, the oil doesn’t get consumed nor leak, and wait for it…..It was all purchased for $12 a gallon at the 24 hour super Wal-mart. And this is not good enough because???????

One last thought here: If a builder spend many hours talking about super special oils, and how they can fix everything in your life including your 401K, and spend a lot of time talking about this on the net and later comes to a college but has no idea how to install a distributor and set timing, I am going to tease him about spending a lot of time thinking about synthetic oil, an answer in search of a valid question,  when he needed to be reading about the fundamentals of his engine.

Do you want to try synthetic? Look at Amsoil 10w-30. We ran this for many years. It is great stuff. The reason why I trust it is that it has long been proven to work in airplane engines with 100LL. In the 1980s it was marked for general aviation aircraft. It has a track record of working. BTW, I have never seen a Corvair engine run any different pressure or temp with synthetic oil. Anyone who has was probably imagining it because they wanted to see it. The one thing that isn’t imaginary is synthetic oils ability to leak out of engines. If your engine leaks a little with mineral oil, try switching to synthetic, flying an hour and looking at the bottom of your plane. You will be temped to yell out “Jed’s a Millionaire!” (A&P mechanics do this when the spot a giant oil leak.)

Very Important: You should put additional ZDDP in the break in oil, and there is no harm in running it during the rest of the life of the engine. You can learn more about it at this link:

If you would like some more information on why ZDDP is important, read this link:

Core Engine needed, Portland OR. Payback time….


As mentioned in our last story, Zenith builder Spenser Rice, age 15, is our youngest builder. He is working on a plans built 601HD. In addition to going to school, he works to fund his airplane budget. He has been hunting for a core engine for his project. This is kind of tough, because he can’t just jump in the car and go look at them. He has found a few leads, but nothing has panned out yet.

A few months ago, Spenser wanted to place an order with us for a manual and a disassembly DVD. When I learned a little more about his age and project, Grace and I sent him a full set of manuals and DVD’s at no cost to him. I carefully explained that he did not owe us anything for this, and it was not charity. I was simply repaying a 35 year old debt to Mr. Harold Kreiss, a man I has last seen in NJ in 1978.

Mr Kriess was the guidance counselor at Millburn Jr. High School when I was Spenser’s age. In a nutshell, I was a rotten kid at 15. I was a good student academically, but I had terrible friends, and they didn’t have to twist my arm very hard to get me to go along. In a short time, I was in frequent trouble. I once drew detention 22 days in a row. Most of this was over fighting. at 5’7′-130 lbs I was not on the winning end of this, but I didn’t back down from bullies. After an incident that Mr Kriess would have been justified in turning me over to the Juvenile Officer at MPD, he chose to do something different. He spoke with me for 30 minutes and found out that I really liked airplanes. On his own personal time he went to West Caldwell airport, and arranged to get me a weekend job as a helper at an Aircraft Maintenance shop. Although I thanked him at the time, you are not aware at 15 that it wasn’t really this mans job to do this. You would really have to be a clairvoyant optimist to think that anything good would come the effort, or my life for that matter. Harold Kriess was such an optimist, just when I really needed to have someone believe there was something good hiding in me.

If any of you Corvair builders out there have an outstanding debt to your own Mr Kriess, let me know and I will share Spenser’s email address with you. Perhaps someone in his part of the country can find a good core? Maybe several people who were the recipients of unwarranted generosity in your formative years would like to contribute to its purchase cost? I will gladly tell you that it felt pretty good to unload a part of my 35 year old account with Mr Kriess.

I would like to have Spenser meet Dick Otto, 92, on the northern leg of our October CA tour.( Dick Otto in California, S.R.B. (Senior Ranking Builder)  ) I like the idea that they have a 77 year age spread. Let’s see if we can find Spenser a core so that he can compare engine building notes with Dick in October.-ww

Mail Sack 6/25/13, Cell Phones and Upcoming Events.


Here is a sample of the mail:


on the subject of  Turtles and Cell Phones, 6/24/13.

Zenith 750 builder/flyer (O-200) Jimmy Young wrote:

William, I grew up as a little turd hunting anything that moved with my BB gun. I don’t know why I wanted to kill every bird I saw, probably because I was just young, stupid, & dealing with something the wrong way. I was that “self-absorbed child” you spoke of. The prettier the bird the harder I tried. Cardinals, Blue Jays, they seemed more “valuable” than a common sparrow. Somehow, I gradually over the years grew into a more respectable game law-abiding young man by the time I was in my late teens. Today at 58, I haven’t pulled a trigger on anything other than an occasional rat with my Benjamin pellet gun in my suburban back yard in probably 30 years. Not because I am an Anti-Hunter or tree hugger, but because I simply don’t care to kill animals anymore unless it is necessary.

As I reflect back on my life & fast forward to the last 7 years, my best years to date & the only years of aviation and plane building, I fly around in my Zenith 750 just like those birds do. There is irony in this, now I’m the little bird. I had good flight training, do a good preflight, and respect the laws of the 3 referees you frequently refer to. Yet on Sunday, I was about to take off with a buddy for a little local flying. I had just added some fuel to both tanks, did my preflight, and was taxiing out on our grass strip when I heard some banging on the side of my fuselage. It was my buddy who had jumped out of his Taylorcraft & run up to my plane to warn me I had fuel pouring out of my left wing. I shut the engine down and found I had left the fuel cap off that tank during refueling. Not that this particular mistake would have necessarily turned into a disaster, but it woke me up to the fact that I missed something that should have been obvious because it wasn’t on my checklist and I had not been thorough. It is now.

The importance of your posts on safety cannot be stressed enough. Thanks for teaching me a lot about engines over the last few years and for sharing what you know with us, it is much appreciated. I read your column every time I see there is a new post. Jimmy Houston, TX

Zenith 601XLB builder/flyer Dr. Gary Ray writes:

Disrespect for life, disrespect for the lives sacrificed in order to build this country, disrespect for a person standing right in front of them, all the while expecting you to do more for them than they are willing to do for themselves.   The moral, never turn your back to one of these people since this disrespect flows outward in all directions.  They will not be good friends, customers or citizens.  There can not be any mutually beneficial relationship with somebody that displays this trait.

Builder Doug Wright writes:

William, Back in the early 1980’s I served two and a half years at the garden spot of the army, Ft. Polk, Louisiana.  Now don’t get me wrong, Ft. Polk really is a pretty place and because I have always tried to find the good in anywhere I have lived I could never understand why so many people had such a negative opinion of the post.  Maybe it was because just a few years earlier Ft. Polk was the last stateside stop many guys had before heading to Vietnam.  Tigerland!

One of the negative aspects of Ft. Polk and the surrounding area was the number of turtles that would migrate across the road and get squashed by the traffic. Here I was a rough and tough combat engineer and on more than one occasion I would pull over and save some poor turtle from imminent destruction.  I am sure there are some who witnessed this and thought I was a big softy, but I really did not care.  We were training to meet the Soviets in the Fulda Gap and I gladly would have killed as many of those folks as the situation called for but it always bothered me to see those turtles run over in the middle of the road. Doug, Stillwater, OK

Zenith 750 builder Dan Glaze wrote:

William, in all my years spent at various Air Force Bases around the world, when Old Glory was run up the mast at the start of day, every body on that base snapped to attention,if you could not see the flag from where you were, you needed to know where she was and be facing that way,at night, when tapps played we gave her the same respect, and if you didnt have a big lump in your throat thinking about all the men and women that gave their life for her then you needed more training, and teachers were not hard to find. I am a pretty laid back guy but will not tolerate disrespect for Country or Flag,  Dan-o

Zenith 650 builder Paul Normandin wrote:

Zenith 650 Builder William, at about the time you were driving past that poor turtle to get your mail yesterday I was driving into work. I live in New Hampshire, work in Massachusetts and have to drive 3 badly congested highways in the process. In the course of this drive I was cut off three times (coincidentally, all three drivers were driving Acuras). In each instance the offending driver had a cell phone glued to their ear, two of whom were also gesticulating with their other hand. Apparently they were using their prehensile knees to drive. I have had a mobile phone since 1987, my original was a Motorola Bag phone, and I have had the same mobile number all that time. At no point in 26 years have I used my phone in any way that would endanger myself (bad enough) or others (worse). Maybe being a life long motorcycle rider has made me more aware of the stupidity of not having 100% of my attention on the task at hand. I can’t even in good conscience state, “These damn kids and their cell phones!” as I have seen just as many idiots our age engaged in the same bad behavior. As far as your shutting off the ignorant man who took a call while in the middle of talking to you, I would have done the same thing. There are a number of businesses locally, coffee shops, sandwich shops and other service related establishments, that have signs stating in no uncertain terms that they will not wait on anyone who is using a cell phone. Bully for them and for you. At some point we will meet at a College and you will periodically see me checking my phone. The major difference between the folks you were referencing and myself is this; more than anything else, my cell phone is a time piece and not a communication device (I haven’t owned a watch in almost 20 years)! Paul P.S. And everyone should SHUT UP during the National Anthem!

International Aviator of adventure Tom Graziano wrote:

William, The ignorance, stupidity and rudeness of the spoiled sheeple in Amerika nowadays amazes me every time I return stateside. It also makes me wonder if the hardships and sacrifices our men and women overseas have been enduring are worth it. Then….I think of the people who think and act as you and I do, and I conclude that it is – because of them.

Went to a breakfast fly-in at one of the local airfields, recently. Untowered airport, left traffic – both patterns, and a favorite of guys flying antiques and ultralights. Lots of planes flew in. So, I’m getting ready to take off when I hear some knucklehead calling that he’s entering the downwind for a right base. WHAT!?! I inform him that both patterns are LEFT traffic and look up in time to see him  blasting along at pattern altitude going in the OPPOSITE direction of normal traffic. He smugly tells me that, since he didn’t hear anyone in the pattern, he decided to just come straight in and do right traffic. Apparently, it never occurred to Mr. Einstein that some aircraft don’t have radios, that radios don’t always work, and that there actually have been cases of pilots not being on the correct on frequency or not making calls. He was enlightened when he landed, but he was an arrogant sort, so it probably didn’t do any good. Just proves that we can’t regulate stupid….

Pietenpol builder and ATP Dave Aldrich wrote:

Hi William I once had an Airbus engineer ask the hypothetical question “Suppose the chances of your cell phone interfering with the aircraft are one in a million.  Pretty good odds.  There are roughly 5,000 commercial flights a day.  How do you like your odds now?”  The part B of all this is, well let’s just suppose that one cell phone doesn’t cause any interference (there’s probably some empirical data to support this) but has anyone done any kind of test with multiple cell phones, wi-fi enabled computers and idiot pads?  The electro-magnetic spectrum cringes…

I’ve done a load analysis on the Pietenpol I’m building and can’t figure out how to get more than a 12 amp load, even considering the 80% requirement.  That’s with position lights/strobes, radio, transponder, ignition, and electric gauges.  If you wanted to go all electronic, the Dynon simple EFIS displays draw about 1 amp each.  Yes, a landing light, heated pitot, a fancy autopilot and the gee whiz almost real life displays will get you above the 20 amp threshold but how many folks really need all those toys?  If you did a lot of long cross-country flying, an autopilot could be considered almost essential but you could still stay within the 1 alternator power budget with careful selection of components.  Experimental aviation is supposed to be fun, not an extension of your kid’s X-Box.  You want to fly hard IFR at night?  Get a Baron or a Caravan.  You want to fly hard IFR at night in an experimental?  Get your head examined.  I’m not saying it can’t be done but the experimental pilot who doesn’t do night approaches to minimums for a living is going to end up as an unfortunate statistic when he/she tries it.  It’s a waste of time and money to build to that capability.  Simple and, as William preaches — proven– is the way to go.  Stepping down off the soap-box now…

Zenith builder Spenser Rice  wrote:

I can’t agree with you more William. Especially the kids talking through our beloved country’s anthem.  Being 15 I’m ashamed that my generation has no respect and make the few good kids look bad as well. Spencer Rice

Spenser, you have nothing to apologize for. Here you are regarded as an individual, and you are not responsible for the behavior of other people just because they are your age. Sad but true, people with little respect or consideration come in all ages these days. To all of the rest of you out there, I want to introduce you to Spenser, who at 15 is our youngest builder. Many of his aviation mentors have sent me glowing reports on how serious he is, and how hard he works to earn his way in aviation. I would like to get a more detailed profile on him soon, so a number of you successful aviators can offer guidance on his progress. Spenser, write me back and let me know if you have found a workable core engine yet.

Zenith 650 builder Becky Shipman wrote:

I used to bicycle regularly. I was a lot less wealthy then. I remember seeing a turtle in the middle of the road, and stopping on the side to pick him up and carry him to the other side so he would be safe. While I was waiting to go get him, one of the cars hit him. I don’t know if it was intentional, I also don’t know if I created a distraction that made it less likely the driver would see the turtle. He was still alive, and I eventually got him to safety, but I don’t know if he survived.

Mostly I just try to be an observer of nature, but sometimes I’ll try and help if I can. And sometimes I won’t. I had a neighbor call me over to help save a toad from a snake. I looked at it and figured sometimes toads are eaten by snakes, and that’s not much fun for the toad but necessary for the snake to live. I don’t know if I got her to understand why I wouldn’t interfere. Just some thoughts. Becky Shipman


on the subject of Upcoming events, Airshows and Colleges #26-28.

Zenith builder Vic Delgado  wrote:

William! Many Thanks go to you, Kevin and Shelley for planning on hosting Corvair College #28 in Texas. I am so looking forward to being there! The last one they hosted CC #22 was an absolutely awesome experience. I am planning on hopefully making this the one I can graduate with a running engine from!  Don’t forget to bring your Tee shirt and shorts, You know Texas weather is beautiful in March!

Builder Bruce Culver wrote:

Eureka! I will announce my intention to attend the 2014 CC#28 in Texas…..:-)  This will work out beautifully as far as getting a core and being able to do a lot of the prep work. Outstanding!

Zenith 650 builder Paul Normandin wrote:

While I would dearly love to attend the Zenith Corvair College I know I will never be ready. I must set my sights on November and the lovely state of South Carolina instead. That depends on my getting the bloody heads off my core so I can get them out to Falcon as they are being exceedingly stubborn!

Parting shot, from builder Dan Branstrom:

I was doing some substitute teaching in a class that was English as a Second Language when it came time for the Pledge of Allegiance.  There were kids from a number of different countries.  The great majority of students stood.  Some of those didn’t recite the Pledge.  I didn’t have a problem with that, because I understood that they might not be citizens. When it was over, I was angry, but I decided to make a lesson out of it.  Realizing that some of them would have a problem understanding me, I spoke slowly so that their friends could tell them what I’d said.

I explained that my father was an immigrant, who arrived in this country not speaking the language, so I somewhat understood the situation they were in. What I told them was that I understood that they might not be citizens, and I didn’t expect them to recite the pledge, because they weren’t.   I then told them that in not standing respectfully, they were giving ammunition to all the people who wanted to deport all foreigners, because it showed disrespect to the country they were in. I had the feeling that they understood what I told them. I expect the same respect from citizens.