No Avgas 100LL by 2030 ??

[skippydiesel]

I don

On 26/07/2026 at 10:41 AM, kgwilson said:

A paper published in 2010 by BP relating to petrol life in vehicle fuel tanks is just as relevant today as it was back then. PDF file attached

petrol-life-vehicle-tanks.pdf 85.8 kB · 14 downloads

The reference made has no date on it, however by my reading seems to be more recent/current;

 

https://www.bp.com/content/dam/bp/country-sites/en_au/australia/home/products-services/fuels/opal-factsheet-storagehandling.pdf

 

😈

[turboplanner]

2 hours ago, facthunter said:

I can't see how your above post relates to anything I have just  said. Please desist from this Practice in the future. Nev

You're right. I attached my answer to thr wrong quote. This was the correct quote:

"Ask Jack Vevers. Stale fuel belongs in Lawn Mowers,  Nev"

[danny_galaga]

Once there is no 100LL it will not be a big deal for fuel suppliers to provide a guaranteed quality of unleaded fuel to airfields and airports. It's not like old mate is pulling up to the 7/11 in his Bonanza to fuel up.

 

What do the suppliers do now with 100LL? whatever it is, do the same with unleaded 🤷‍♂️

Edited July 28 by danny_galaga

[skippydiesel]

8 minutes ago, danny_galaga said:

 

What do the suppliers do now with 100LL? whatever it is, do the same with unleaded 🤷‍♂️

I suspect that fuel, designated for aircraft, has a lot more associated paperwork (=$$$)😈

[skippydiesel]

On 14/07/2026 at 7:34 AM, kgwilson said:

My engine has only done 400 or so hours but the risks of using Avgas compared to Automotive petrol are minimal with appropriate management and care. And the engine is all the better for it.

Please clarify - are you using more or less than 30% AvGas in your Rotax?😈

[skippydiesel]

On 12/07/2026 at 7:18 PM, BrendAn said:

the tecnam and eurofox trainers at latrobe valley always ran avgas until the mogas tank was installed. didn't bother them at all.

No offence intended - This is a misleading statement. The engine may not be bothered, however its owners should.

 

Rotax advise that when using more than 30% AvGas in their 9 Range additional servicing/maintenance is required.

 

Rotax 9's are designed to run on ULP.

• They will run on AvGas, with additional servicing/ maintenance required, due to lead build up within the engine/g box.
• There is no performance gain with AvGas below 10,000 ft and above that, marginal.
• Avgas usually very much more expensive than ULP. Current fuel prices, due to middle east wars, may reduse the margine.

From imperfect memory - When using AvGas at above 30%:

• Oil changes reduced from 100 hrs to 50 hrs ie twice the cost.
• Gearbox inspection reduced from 1,000 hrs to 600 hrs ie almost twice the cost.

😈

[BrendAn]

12 minutes ago, skippydiesel said:

No offence intended - This is a misleading statement. The engine may not be bothered, however its owners should.

 

Rotax advise that when using more than 30% AvGas in their 9 Range additional servicing/maintenance is required.

 

Rotax 9's are designed to run on ULP.

• They will run on AvGas, with additional servicing/ maintenance required, due to lead build up within the engine/g box.
• There is no performance gain with AvGas below 10,000 ft and above that, marginal.
• Avgas usually very much more expensive than ULP. Current fuel prices, due to middle east wars, may reduse the margine.

From imperfect memory - When using AvGas at above 30%:

• Oil changes reduced from 100 hrs to 50 hrs ie twice the cost.
• Gearbox inspection reduced from 1,000 hrs to 600 hrs ie almost twice the cost.

😈

No offence intended either but I think the lames that look after the club trainers would be far more experienced and familiar with the maintenance requirements of a 912 on avgas than a rec pilot / enthusiast.

Edited July 28 by BrendAn

[facthunter]

Have there been images of engine and gearbox lead build ups in Rotax 9xx Motors? I'd like to see some evidence. The more Blow by the More lead transferred to the Engine oil. Most larger engines have  reduction gears using the Common oil supply. 100LL(Low Lead) is much LESS lead that any other Avgas like 130/145. .  I've NEVER seen lead build ups in stripped motors that run on 100LL  The filthiest Motor I've ever seen stripped was in a Grumman Cropduster that had run Auto Petrol always. It was gummed up like no other aero engine I've ever seen. Nev

Edited July 28 by facthunter

[BrendAn]

1 minute ago, facthunter said:

Have the been images of engine and gearbox lead build ups in Rotax 9xx Motors? I'd like to see some evidence. The more Blow by the More lead transferred to the Engine oil. Most larger engines have  reduction gears using the Common oil supply. 100LL(Low Lead) is much LESS lead that any other Avgas like 130/145. .  I've NEVER seen lead build ups in stripped motors that run on 100LL  The filthiest Motor I've ever seen stripped was in a Grumman Cropduster that had run Auto Petrol always. It was gummed up like no other aero engine I've ever seen. Nev

The 2 912s at Latrobe valley ran on avgas for a long time with no issues that I have heard about. They run on mogas now because it is available onsite.

[kgwilson]

20 hours ago, skippydiesel said:

I don

The reference made has no date on it, however by my reading seems to be more recent/current;

 

https://www.bp.com/content/dam/bp/country-sites/en_au/australia/home/products-services/fuels/opal-factsheet-storagehandling.pdf

 

😈

Yes it does. At the bottom of each page it states "Issued January 2010, supercedes Feb 2005."

[kgwilson]

1 hour ago, skippydiesel said:

Please clarify - are you using more or less than 30% AvGas in your Rotax?😈

I have a Jabiru 3300A engine as specified in an earlier post. I only use Avgas if I can't get Automotive 95 or 98 ULP.

[facthunter]

Why is the 30% figure critical? . Nev

[skippydiesel]

1 hour ago, BrendAn said:

No offence intended either but I think the lames that look after the club trainers would be far more experienced and familiar with the maintenance requirements of a 912 on avgas than a rec pilot / enthusiast.

I am paraphrasing Rotax recommendations, which for aircraft used for hire/reward (training) are a requirement ie non negotiable. Whoever owns the aircraft, you referenced will have higher operating costs, than a similar ULP power aircraft  - no doubt passed on the the customer/students.

 

Has nothing to do with my qualifications, skill set, knowledge.

 

There are plenty of Rotax 9 users who do use AvGas (seems to be quite popular in the USA) however they accept the additional costs associated with their choice. From my reading, various N American based forums, obtaining ULP without ethanol can be difficult - this, convention  & convenience (AvGas being readily available at most airfields) may be the reasons. 😈

[skippydiesel]

59 minutes ago, kgwilson said:

Yes it does. At the bottom of each page it states "Issued January 2010, supercedes Feb 2005."

You must be looking at a diffrent document - The one I referenced (opal-factsheet-storagehandling.pdf ) has no date. It just reads as a more up-to-date/resent document than yours.😈

[skippydiesel]

56 minutes ago, kgwilson said:

I have a Jabiru 3300A engine as specified in an earlier post. I only use Avgas if I can't get Automotive 95 or 98 ULP.

Thanks KG,

 

I don't know very much about Jabs however it seem to me, when using AvGas, they do not suffer from the lead fowling that Rotax 9 devlope.😈

[skippydiesel]

2 hours ago, BrendAn said:

No offence intended either but I think the lames that look after the club trainers would be far more experienced and familiar with the maintenance requirements of a 912 on avgas than a rec pilot / enthusiast.

Be very careful about assumptions about LAMES maintaining Rotax engines. 

I have met LAME's who knew next to nothing about Rotax engines and further more did not want to know.

So closed minded are some , I know of one instance where the training organisation, acquired a Rotax powered aircraft, to offer cheaper flight training. The LAMES  refused to mainatine it and the school had to sell it off.😈

[BrendAn]

2 hours ago, skippydiesel said:

Be very careful about assumptions about LAMES maintaining Rotax engines. 

I have met LAME's who knew next to nothing about Rotax engines and further more did not want to know.

So closed minded are some , I know of one instance where the training organisation, acquired a Rotax powered aircraft, to offer cheaper flight training. The LAMES  refused to mainatine it and the school had to sell it off.😈

i know the people i was talking about pretty well. they do a lot of work on rotax as well as ga.

they also do most of the l4 raa work in the area.

[facthunter]

 Tetra-ethyl  lead.( TEL ) only helps EXHAUST valve seats when the Metal temps are hot enough for it to be a fluid  and act as a lubricant. The Rotax Alloy Liquid cooled heads do not operate at High enough temps  for this to consistently happen and a build up occurs where some breaks away and a damaged (eroded) valve seat is possible with compression loss. Sometimes just running with Mogas will correct it. I'd still Like to Know the Nature of the alleged gearbox and engine damage and some actual evidence. Nev

[Thruster88]

40 minutes ago, facthunter said:

 Tetra-ethyl  lead.( TEL ) only helps EXHAUST valve seats when the Metal temps are hot enough for it to be a fluid  and act as a lubricant. The Rotax Alloy Liquid cooled heads do not operate at High enough temps  for this to consistently happen and a build up occurs where some breaks away and a damaged (eroded) valve seat is possible with compression loss. Sometimes just running with Mogas will correct it. I'd still Like to Know the Nature of the alleged gearbox and engine damage and some actual evidence. Nev

A quick search returned zero images of rotax gearbox issues after running 100ll. There are numerous images showing known issues with lycoming, Continental and jabiru engines.

[BrendAn]

While on the subject. I got told the other day that I have to add a spacer or increase the combustion chamber size on my Jabiru 2200a to use unleaded. I have never heard or read anything about this before.

[skippydiesel]

1 hour ago, Thruster88 said:

 returned zero images of rotax gearbox issues after running 100ll. There are numerous images showing known issues with lycoming, Continental and jabiru engines.

It must have been a very "quick search" indeed & why images ? when Rotax are quite specific about the use of AvGas.

 

I doubt if there is a Rotax owner who does not know of the increased service/maintenance requirements, due to lead,  when running the 9 series engines on predominately AvGas.

 

My quick search revealed the following:

 

• "The official advisory and technical guidance for using leaded AvGas in Rotax 912 and 914 series engines is outlined in Rotax Service Instruction Rotax Service Instruction SI-912-016 (Selection of Suitable Operating Fluids). Leaded fuel increases lead deposits, spark plug wear, and oil sludge, requiring tightened maintenance intervals if used for more than 30% of operating time. "
• "Oil and Filter Changes: Must be reduced (from 100 hrs) to every 50 hours (or ideally 25 hours) instead of normal intervals when running mainly on leaded AvGas. "
• "Gearbox and Clutch: Extra wear checks (@ 600 hrs) on the overload/slipper clutch and removal of lead sludge accumulated in the crankcase and oil lines (ULP interval 1,000 hrs)"

 

Further a read of the 912 Service Schedule, will back up the above statements.😈

Edited July 28 by skippydiesel

[skippydiesel]

1 hour ago, BrendAn said:

While on the subject. I got told the other day that I have to add a spacer or increase the combustion chamber size on my Jabiru 2200a to use unleaded. I have never heard or read anything about this before.

I cant make an informed comment about your Jab engine, however in the past, cars exported from Europe/UK where high Octane automotive fuel was available  & specified, often had their compression ratio reduced (thicker head gasket/spacer)to facilitate the lower octane fuels then available in Australia.

 

My home airfield is over run with Jabs. I stand to be corrected, they run on 95 - 98 RON automotive fuel.😈

[Thruster88]

37 minutes ago, skippydiesel said:

It must have been a very "quick search" indeed & why images ? when Rotax are quite specific about the use of AvGas.

 

I doubt if there is a Rotax owner who does not know of the increased service/maintenance requirements, due to lead,  when running the 9 series engines on predominately AvGas.

 

My quick search revealed the following:

 

• "The official advisory and technical guidance for using leaded AvGas in Rotax 912 and 914 series engines is outlined in Rotax Service Instruction Rotax Service Instruction SI-912-016 (Selection of Suitable Operating Fluids). Leaded fuel increases lead deposits, spark plug wear, and oil sludge, requiring tightened maintenance intervals if used for more than 30% of operating time. "
• "Oil and Filter Changes: Must be reduced (from 100 hrs) to every 50 hours (or ideally 25 hours) instead of normal intervals when running mainly on leaded AvGas. "
• "Gearbox and Clutch: Extra wear checks (@ 600 hrs) on the overload/slipper clutch and removal of lead sludge accumulated in the crankcase and oil lines (ULP interval 1,000 hrs)"

 

Further a read of the 912 Service Schedule, will back up the above statements.😈

I am well aware of the rotax requirements.  Find me a picture of a lead sludged rotax gearbox. 

[danny_galaga]

10 hours ago, Thruster88 said:

I am well aware of the rotax requirements.  Find me a picture of a lead sludged rotax gearbox. 

What does it matter if you can find a picture or not? What's important is what the manufacturer says.

[facthunter]

It's reasonable to ask for evidence. You learn that the Hard way. From experience. A picture is worth a Thousand words. Manufacturers say "Filled for life" for some gearboxes. In Practice not a good idea. Nev