---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Thu 10/14/04: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:25 AM - Rotax 912 80 hp rough running (Peter Cowan) 2. 07:06 AM - Re: Rotax 912 80 hp rough running (Lowell Fitt) 3. 08:05 AM - Re: ENGINE OIL (Hinde, Frank George (Corvallis)) 4. 08:58 AM - Re: ENGINE OIL (Gene Smith) 5. 09:31 AM - Re: ENGINE OIL (Konrad Werner) 6. 09:54 AM - Re: ENGINE OIL (Tracy Crook) 7. 10:23 AM - Re: ENGINE OIL (Gene Smith) 8. 02:57 PM - Re: ENGINE OIL (Vic Jacko) 9. 07:52 PM - Slobovia Outernational BBQ 2 day warning (Charlie England) 10. 08:45 PM - Aviation Oil Vs Motor oil (Synthetic) (Pete Marshall) ________________________________ Message 1 _____________________________________ Time: 04:25:57 AM PST US From: "Peter Cowan" Subject: Engines-List: Rotax 912 80 hp rough running --> Engines-List message posted by: "Peter Cowan" This early 1990s engine has under 200 hours on it. It runs quite rough in the mid range especially 4000 but smooths out at over 5000. I've balanced the carbs at 2500 rpm as per Lockwood's instructions. This seemed to improve things but unless I'm imagining it the rough running has gradually got worse.The prop is balanced . One plug is quite sooty as is the exhaust stack out of the muffler the other plugs are quite clean. One suggestion is to check the plugs (even though they are only 15 hours old) because thsy could still be bad. I'll do that. Temperatures are dropping here (10 to 15 C, 45-55 F ) Anyone experienced this and done something that worked? Thanks Peter ________________________________ Message 2 _____________________________________ Time: 07:06:05 AM PST US From: "Lowell Fitt" Subject: Re: Engines-List: Rotax 912 80 hp rough running --> Engines-List message posted by: "Lowell Fitt" Peter, I don't know if this is cause and effect, but I changed out my plug wires and got rid of most of my mid range roughness. My understanding is that some roughness is somewhat normal at 4-4500 rpm with the 912. The plug wires are 7mm diameter and unscrew from all the fittings - plug and coil. The rubber covering from the wires can be removed and reused. Kneed it a bit to find the adhesive that holds it on the plug wire and you can break the bond and slide it off. Use dielectric grease on the ends when reassembling the units. Lowell ----- Original Message ----- From: "Peter Cowan" Subject: Engines-List: Rotax 912 80 hp rough running > --> Engines-List message posted by: "Peter Cowan" > > This early 1990s engine has under 200 hours on it. It runs quite > rough in the mid range especially 4000 but smooths out at over > 5000. I've balanced the carbs at 2500 rpm as per Lockwood's > instructions. This seemed to improve things but unless I'm > imagining it the rough running has gradually got worse.The prop > is balanced . One plug is quite sooty as is the exhaust stack out > of the muffler the other plugs are quite clean. > One suggestion is to check the plugs (even though they are only > 15 hours old) because thsy could still be bad. I'll do that. > Temperatures are dropping here (10 to 15 C, 45-55 F ) > Anyone experienced this and done something that worked? > Thanks > Peter > > ________________________________ Message 3 _____________________________________ Time: 08:05:01 AM PST US Subject: RE: Engines-List: ENGINE OIL From: "Hinde, Frank George (Corvallis)" --> Engines-List message posted by: "Hinde, Frank George (Corvallis)" I'm beginning to think that Aeroshell is snake oil....But befor I get flamed, let me explain. So far the most logical argument is that cos airplane engines are aircooled they burn a lot more oil (true to a degree I think). Thus you want an oil that is deemed to be "Ashless" so the oil doens'nt end up depositing in the combustion chambers. The real questions is "does it really make THAT much difference?"....In the many car engines I've stripped there is always a build up of carbon anyways...Is not the same true of aero engines. Does a little more coke using automotive 20W-50 meant the thing has to be stripped down more often to decoke it? I doubt it but I don't know and when I buy my new IO360 I know the warranty will not cover it if it is damaged by using automotive oil. In the end, even if 20W-50 is perfectly OK its going to take a brave individual (or one with a run out engine) to try it. So far I'm glad the warranty will kind of cover it if using autofuel.....Looking at the several cases of Castrol 20W-50 sure is tempting though! Frank -----Original Message----- From: owner-engines-list-server@matronics.com [mailto:owner-engines-list-server@matronics.com] On Behalf Of WRBYARS@aol.com Subject: Engines-List: ENGINE OIL --> Engines-List message posted by: WRBYARS@aol.com Ever since I've had airplanes, (about 40 years now), I've used Aero Shell oil of some type, however for some time now I've been seeing more advertising, reading articles and hearing folks talk about "CASTROL" oil. I've used this brand in my cars and trucks for years with very good results, but never in an aircraft engine. Please give me input on the use of CASTROL, as opposed to AERO SHELL, PHILLIPS, etc. for my Lycoming 0290-D. Thanks Bill == direct advertising on the Matronics Forums. == == == ________________________________ Message 4 _____________________________________ Time: 08:58:07 AM PST US From: "Gene Smith" Subject: Re: Engines-List: ENGINE OIL --> Engines-List message posted by: "Gene Smith" OK, I'm going to throw some fat into the fire!..This is success so far...(Lordy help me, I'm knocking on wood, and don't want to stir things up too much)...For the last 10 years (RV-4/160 Lyc.) I have been mixing 50/50% 3qts of AeroShell and 3qts of Mobil 1 synthetic (15w50) at each oil change, and I mix 50/50% 100LL and Premium Mogas...I have never had any problems at all including spark plugs...I change the oil when it starts to turn dark, probably at about 20 hours, based on the theory that the cheapest and best thing you can do for your engine is change oil often. I pulled a jug recently to for a "look-see" to determine what was going on inside because of the controversy over synthetic oil in big engines...I got quite a surprise...The inside of the engine was absolutely clean and golden with no "sludge" at all. Remember, this is ME, I do not recommend this for any of you out there, you make your own decisions...Remember, we are experimental, but not test pilots.......................Good luck.....................CHEERS!!!!......................Gene Smith. ----- Original Message ----- From: "Hinde, Frank George (Corvallis)" Subject: RE: Engines-List: ENGINE OIL > --> Engines-List message posted by: "Hinde, Frank George (Corvallis)" > > I'm beginning to think that Aeroshell is snake oil....But befor I get > flamed, let me explain. > > So far the most logical argument is that cos airplane engines are > aircooled they burn a lot more oil (true to a degree I think). Thus you > want an oil that is deemed to be "Ashless" so the oil doens'nt end up > depositing in the combustion chambers. > > The real questions is "does it really make THAT much difference?"....In > the many car engines I've stripped there is always a build up of carbon > anyways...Is not the same true of aero engines. > > Does a little more coke using automotive 20W-50 meant the thing has to > be stripped down more often to decoke it? > > I doubt it but I don't know and when I buy my new IO360 I know the > warranty will not cover it if it is damaged by using automotive oil. > > In the end, even if 20W-50 is perfectly OK its going to take a brave > individual (or one with a run out engine) to try it. > > So far I'm glad the warranty will kind of cover it if using > autofuel.....Looking at the several cases of Castrol 20W-50 sure is > tempting though! > > Frank > > > -----Original Message----- > From: owner-engines-list-server@matronics.com > [mailto:owner-engines-list-server@matronics.com] On Behalf Of > WRBYARS@aol.com > To: engines-list@matronics.com > Subject: Engines-List: ENGINE OIL > > > --> Engines-List message posted by: WRBYARS@aol.com > > Ever since I've had airplanes, (about 40 years now), I've used Aero > Shell > oil of some type, however for some time now I've been seeing more > advertising, > reading articles and hearing folks talk about "CASTROL" oil. I've used > this > brand in my cars and trucks for years with very good results, but never > in an > aircraft engine. > > Please give me input on the use of CASTROL, as opposed to AERO SHELL, > PHILLIPS, etc. for my Lycoming 0290-D. > > Thanks > Bill > > > == > direct advertising on the Matronics Forums. > == > == > == > > ________________________________ Message 5 _____________________________________ Time: 09:31:43 AM PST US From: "Konrad Werner" Subject: Re: Engines-List: ENGINE OIL --> Engines-List message posted by: "Konrad Werner" Dear Gene, So what is the benefit of mixing a very good Aviation oil with a very good Auto Oil? Can't be Money $aving$ at the price of Mobil-1. Do you drive your RV-4 a lot on the long taxiways? P.S. I think YOU ACTUALLY ARE a test pilot!!! >>> ...Remember, we are experimental, but not test pilots...Goodluck...CHEERS!!!! Gene Smith.<<< Konrad ----- Original Message ----- From: Gene Smith To: engines-list@matronics.com Sent: Thursday, October 14, 2004 9:58 AM Subject: Re: Engines-List: ENGINE OIL --> Engines-List message posted by: "Gene Smith" OK, I'm going to throw some fat into the fire!..This is success so far...(Lordy help me, I'm knocking on wood, and don't want to stir things up too much)...For the last 10 years (RV-4/160 Lyc.) I have been mixing 50/50% 3qts of AeroShell and 3qts of Mobil 1 synthetic (15w50) at each oil change, and I mix 50/50% 100LL and Premium Mogas...I have never had any problems at all including spark plugs...I change the oil when it starts to turn dark, probably at about 20 hours, based on the theory that the cheapest and best thing you can do for your engine is change oil often. I pulled a jug recently to for a "look-see" to determine what was going on inside because of the controversy over synthetic oil in big engines...I got quite a surprise...The inside of the engine was absolutely clean and golden with no "sludge" at all. Remember, this is ME, I do not recommend this for any of you out there, you make your own decisions...Remember, we are experimental, but not test pilots.......................Good luck.....................CHEERS!!!!......................Gene Smith. ----- Original Message ----- From: "Hinde, Frank George (Corvallis)" To: Subject: RE: Engines-List: ENGINE OIL > --> Engines-List message posted by: "Hinde, Frank George (Corvallis)" > > I'm beginning to think that Aeroshell is snake oil....But befor I get > flamed, let me explain. > > So far the most logical argument is that cos airplane engines are > aircooled they burn a lot more oil (true to a degree I think). Thus you > want an oil that is deemed to be "Ashless" so the oil doens'nt end up > depositing in the combustion chambers. > > The real questions is "does it really make THAT much difference?"....In > the many car engines I've stripped there is always a build up of carbon > anyways...Is not the same true of aero engines. > > Does a little more coke using automotive 20W-50 meant the thing has to > be stripped down more often to decoke it? > > I doubt it but I don't know and when I buy my new IO360 I know the > warranty will not cover it if it is damaged by using automotive oil. > > In the end, even if 20W-50 is perfectly OK its going to take a brave > individual (or one with a run out engine) to try it. > > So far I'm glad the warranty will kind of cover it if using > autofuel.....Looking at the several cases of Castrol 20W-50 sure is > tempting though! > > Frank > > > -----Original Message----- > From: owner-engines-list-server@matronics.com > [mailto:owner-engines-list-server@matronics.com] On Behalf Of > WRBYARS@aol.com > To: engines-list@matronics.com > Subject: Engines-List: ENGINE OIL > > > --> Engines-List message posted by: WRBYARS@aol.com > > Ever since I've had airplanes, (about 40 years now), I've used Aero > Shell > oil of some type, however for some time now I've been seeing more > advertising, > reading articles and hearing folks talk about "CASTROL" oil. I've used > this > brand in my cars and trucks for years with very good results, but never > in an > aircraft engine. > > Please give me input on the use of CASTROL, as opposed to AERO SHELL, > PHILLIPS, etc. for my Lycoming 0290-D. > > Thanks > Bill > > > > direct advertising on the Matronics Forums. > > > > > ________________________________ Message 6 _____________________________________ Time: 09:54:19 AM PST US From: "Tracy Crook" Subject: Re: Engines-List: ENGINE OIL Seal-Send-Time: Thu, 14 Oct 2004 12:53:26 -0400 --> Engines-List message posted by: "Tracy Crook" The TYPE of deposits left by burning oil in the combustion chamber makes all the difference. Ashless oil leaves a soft powdery carbon that will not (within limits) cause rings to stick. Typical automotive 4 stroke oil will leave very hard deposits that will. The difference is drastic enough that when I mixed auto oil instead of Aeroshell in the fuel for my O - 100 McCullough drone engine, it seized up after about 1 hour of running. The deposits were obvious upon tear-down. This is an extreme example because the McCullough was very seizure prone and the recommended oil ratio at the time was ridiculously oil-rich, 1 quart of oil to 3 gallons of fuel. Tracy Crook ----- Original Message ----- From: Hinde, Frank George (Corvallis) To: engines-list@matronics.com Sent: Thursday, October 14, 2004 11:04 AM Subject: RE: Engines-List: ENGINE OIL --> Engines-List message posted by: "Hinde, Frank George (Corvallis)" > I'm beginning to think that Aeroshell is snake oil....But befor I get flamed, let me explain. So far the most logical argument is that cos airplane engines are aircooled they burn a lot more oil (true to a degree I think). Thus you want an oil that is deemed to be "Ashless" so the oil doens'nt end up depositing in the combustion chambers. The real questions is "does it really make THAT much difference?"....In the many car engines I've stripped there is always a build up of carbon anyways...Is not the same true of aero engines. Does a little more coke using automotive 20W-50 meant the thing has to be stripped down more often to decoke it? I doubt it but I don't know and when I buy my new IO360 I know the warranty will not cover it if it is damaged by using automotive oil. In the end, even if 20W-50 is perfectly OK its going to take a brave individual (or one with a run out engine) to try it. So far I'm glad the warranty will kind of cover it if using autofuel.....Looking at the several cases of Castrol 20W-50 sure is tempting though! Frank -----Original Message----- From: owner-engines-list-server@matronics.com [mailto:owner-engines-list-server@matronics.com] On Behalf Of WRBYARS@aol.com To: engines-list@matronics.com Subject: Engines-List: ENGINE OIL --> Engines-List message posted by: WRBYARS@aol.com Ever since I've had airplanes, (about 40 years now), I've used Aero Shell oil of some type, however for some time now I've been seeing more advertising, reading articles and hearing folks talk about "CASTROL" oil. I've used this brand in my cars and trucks for years with very good results, but never in an aircraft engine. Please give me input on the use of CASTROL, as opposed to AERO SHELL, PHILLIPS, etc. for my Lycoming 0290-D. Thanks Bill direct advertising on the Matronics Forums. ________________________________ Message 7 _____________________________________ Time: 10:23:42 AM PST US From: "Gene Smith" Subject: Re: Engines-List: ENGINE OIL --> Engines-List message posted by: "Gene Smith" Konrad, Thanks for your response...I suspect your already know the answers to your questions, but here is my logic......From the "big-guys," I read that Aeroshell holds the lead particles and etc. in suspension, but Mobil 1 does not quite do as good in that arena, (but it is slick-as-heck), so why not compromise...I want that "slick" in my engine for friction reduction and heat protection......For the fuel situation, everyone says 100LL has too much lead for our smaller engines, so the 50/50 with no-lead Mogas is obviously another compromise...The cost for Mobil 1 is cheap if you consider $5.00/qt vs. $5k to $8k for a premature overhaul...Surely if you can afford an airplane, you can afford Mobil 1?...Yes, you are correct, Aeroshell is a wonderful oil. Please remember, I advocate none of this for anyone out there, and as I said before, you make your own decisions, for you are the one hanging in those straps, so don't put them to the test......Thanks again...................CHEERS!!!!...............Gene Smith. ----- Original Message ----- From: "Konrad Werner" Subject: Re: Engines-List: ENGINE OIL > --> Engines-List message posted by: "Konrad Werner" > > Dear Gene, > So what is the benefit of mixing a very good Aviation oil with a very good Auto Oil? Can't be Money $aving$ at the price of Mobil-1. > Do you drive your RV-4 a lot on the long taxiways? > > P.S. I think YOU ACTUALLY ARE a test pilot!!! > >>> ...Remember, we are experimental, but not test pilots...Goodluck...CHEERS!!!! Gene Smith.<<< > Konrad > > ----- Original Message ----- > From: Gene Smith > To: engines-list@matronics.com > Sent: Thursday, October 14, 2004 9:58 AM > Subject: Re: Engines-List: ENGINE OIL > > > --> Engines-List message posted by: "Gene Smith" > > OK, I'm going to throw some fat into the fire!..This is success so > far...(Lordy help me, I'm knocking on wood, and don't want to stir things up > too much)...For the last 10 years (RV-4/160 Lyc.) I have been mixing 50/50% > 3qts of AeroShell and 3qts of Mobil 1 synthetic (15w50) at each oil change, > and I mix 50/50% 100LL and Premium Mogas...I have never had any problems at > all including spark plugs...I change the oil when it starts to turn dark, > probably at about 20 hours, based on the theory that the cheapest and best > thing you can do for your engine is change oil often. > > I pulled a jug recently to for a "look-see" to determine what was going on > inside because of the controversy over synthetic oil in big engines...I got > quite a surprise...The inside of the engine was absolutely clean and golden > with no "sludge" at all. > > Remember, this is ME, I do not recommend this for any of you out there, you > make your own decisions...Remember, we are experimental, but not test > pilots.......................Good > luck.....................CHEERS!!!!......................Gene Smith. > > > ----- Original Message ----- > From: "Hinde, Frank George (Corvallis)" > To: > Subject: RE: Engines-List: ENGINE OIL > > > > --> Engines-List message posted by: "Hinde, Frank George (Corvallis)" > > > > > I'm beginning to think that Aeroshell is snake oil....But befor I get > > flamed, let me explain. > > > > So far the most logical argument is that cos airplane engines are > > aircooled they burn a lot more oil (true to a degree I think). Thus you > > want an oil that is deemed to be "Ashless" so the oil doens'nt end up > > depositing in the combustion chambers. > > > > The real questions is "does it really make THAT much difference?"....In > > the many car engines I've stripped there is always a build up of carbon > > anyways...Is not the same true of aero engines. > > > > Does a little more coke using automotive 20W-50 meant the thing has to > > be stripped down more often to decoke it? > > > > I doubt it but I don't know and when I buy my new IO360 I know the > > warranty will not cover it if it is damaged by using automotive oil. > > > > In the end, even if 20W-50 is perfectly OK its going to take a brave > > individual (or one with a run out engine) to try it. > > > > So far I'm glad the warranty will kind of cover it if using > > autofuel.....Looking at the several cases of Castrol 20W-50 sure is > > tempting though! > > > > Frank > > > > > > -----Original Message----- > > From: owner-engines-list-server@matronics.com > > [mailto:owner-engines-list-server@matronics.com] On Behalf Of > > WRBYARS@aol.com > > To: engines-list@matronics.com > > Subject: Engines-List: ENGINE OIL > > > > > > --> Engines-List message posted by: WRBYARS@aol.com > > > > Ever since I've had airplanes, (about 40 years now), I've used Aero > > Shell > > oil of some type, however for some time now I've been seeing more > > advertising, > > reading articles and hearing folks talk about "CASTROL" oil. I've used > > this > > brand in my cars and trucks for years with very good results, but never > > in an > > aircraft engine. > > > > Please give me input on the use of CASTROL, as opposed to AERO SHELL, > > PHILLIPS, etc. for my Lycoming 0290-D. > > > > Thanks > > Bill > > > > > > > > direct advertising on the Matronics Forums. > > > > > > > > > > > > ________________________________ Message 8 _____________________________________ Time: 02:57:02 PM PST US From: "Vic Jacko" Subject: Re: Engines-List: ENGINE OIL --> Engines-List message posted by: "Vic Jacko" Gene, what is your oil burn rate during the 20 hours between changes? Vic ----- Original Message ----- From: "Gene Smith" Subject: Re: Engines-List: ENGINE OIL > --> Engines-List message posted by: "Gene Smith" > > OK, I'm going to throw some fat into the fire!..This is success so > far...(Lordy help me, I'm knocking on wood, and don't want to stir things up > too much)...For the last 10 years (RV-4/160 Lyc.) I have been mixing 50/50% > 3qts of AeroShell and 3qts of Mobil 1 synthetic (15w50) at each oil change, > and I mix 50/50% 100LL and Premium Mogas...I have never had any problems at > all including spark plugs...I change the oil when it starts to turn dark, > probably at about 20 hours, based on the theory that the cheapest and best > thing you can do for your engine is change oil often. > > I pulled a jug recently to for a "look-see" to determine what was going on > inside because of the controversy over synthetic oil in big engines...I got > quite a surprise...The inside of the engine was absolutely clean and golden > with no "sludge" at all. > > Remember, this is ME, I do not recommend this for any of you out there, you > make your own decisions...Remember, we are experimental, but not test > pilots.......................Good > luck.....................CHEERS!!!!......................Gene Smith. > > > ----- Original Message ----- > From: "Hinde, Frank George (Corvallis)" > To: > Subject: RE: Engines-List: ENGINE OIL > > > > --> Engines-List message posted by: "Hinde, Frank George (Corvallis)" > > > > > I'm beginning to think that Aeroshell is snake oil....But befor I get > > flamed, let me explain. > > > > So far the most logical argument is that cos airplane engines are > > aircooled they burn a lot more oil (true to a degree I think). Thus you > > want an oil that is deemed to be "Ashless" so the oil doens'nt end up > > depositing in the combustion chambers. > > > > The real questions is "does it really make THAT much difference?"....In > > the many car engines I've stripped there is always a build up of carbon > > anyways...Is not the same true of aero engines. > > > > Does a little more coke using automotive 20W-50 meant the thing has to > > be stripped down more often to decoke it? > > > > I doubt it but I don't know and when I buy my new IO360 I know the > > warranty will not cover it if it is damaged by using automotive oil. > > > > In the end, even if 20W-50 is perfectly OK its going to take a brave > > individual (or one with a run out engine) to try it. > > > > So far I'm glad the warranty will kind of cover it if using > > autofuel.....Looking at the several cases of Castrol 20W-50 sure is > > tempting though! > > > > Frank > > > > > > -----Original Message----- > > From: owner-engines-list-server@matronics.com > > [mailto:owner-engines-list-server@matronics.com] On Behalf Of > > WRBYARS@aol.com > > To: engines-list@matronics.com > > Subject: Engines-List: ENGINE OIL > > > > > > --> Engines-List message posted by: WRBYARS@aol.com > > > > Ever since I've had airplanes, (about 40 years now), I've used Aero > > Shell > > oil of some type, however for some time now I've been seeing more > > advertising, > > reading articles and hearing folks talk about "CASTROL" oil. I've used > > this > > brand in my cars and trucks for years with very good results, but never > > in an > > aircraft engine. > > > > Please give me input on the use of CASTROL, as opposed to AERO SHELL, > > PHILLIPS, etc. for my Lycoming 0290-D. > > > > Thanks > > Bill > > > > > > == > > direct advertising on the Matronics Forums. > > == > > == > > == > > > > > > ________________________________ Message 9 _____________________________________ Time: 07:52:22 PM PST US From: Charlie England Subject: Engines-List: Slobovia Outernational BBQ 2 day warning --> Engines-List message posted by: Charlie England We hope to see you here at Slobovia Outernational Saturday morning to eat BBQ & talk airplanes. We expect to have a good turnout of homebuilts & classics, with some alternative engines in the mix. Info on Slobovia (MS71) can be found at http://www.airnav.com/airport/MS71 or you can email me direct for driving directions. Charlie flying RV-4; RV-7 wings ________________________________ Message 10 ____________________________________ Time: 08:45:50 PM PST US From: Pete Marshall Subject: Engines-List: Aviation Oil Vs Motor oil (Synthetic) --> Engines-List message posted by: Pete Marshall I know of at least one Canadian fellow using AMSOIL series 2000 20W50 synthetic oil in an aircraft engine, this info from one of our Canadian AMSOIL Dealers. This fellow buys a case every couple on months and has been doing so for about a year. My distributor was telling me that AMSOIL synthetic burns with less ash formation than ashless dispesant aviation oil because of the very few additives used in Amsoil. It is true that AMSOIL synthetic will run about 30 degrees cooler than normal oil. I have proved this to myself by instrumenting my offroad dirtbike oil temperature and recording the temperatures. Getting back to the fuel selection dilemma; an engine builder in Kamloops told me recently that Aviation engines do not have the hardened (stellite) valve seats that are necessary to burn unleaded fuel. He recommended a 50-50 mix of 100 LL with unleaded regular mogas in our O-235 Lycoming. He said that he had had a few engines recently requiring top end overhauls after100 to 200 hours of unleaded mogas. The valves had pounded out the valve seats and tuliped into the heads. We switched back from straight mogas to a 50-50 mix. I notice Lycoming do not mention the use of mogas in their bulletins. It is also true that mogas runs 20 to 30 degrees hotter than even 80 octane AVGAS, and of course 100 LL AVGAS. I have verified this on my Cessna 180 by loading one tank with mogas and the other with pure AVGAS. When the tanks were switched in cruise flight while observing the EGTs, there was a noticeable drop when the tank is switched to AVGAS. For your information. Cheers, Pete Marshall