912S Fuel

[Dave S]

Hi folks,

One question that I have pondered; and still am not exactly sure of it this:

Full synthetic oil is the recommended oil for unleaded auto gas in the Rotax; and, a person cannot use full synthetic oil if leaded fuel is used, for the stated reasons. That all makes sense.

Now - what does a person do who burns mostly unleaded auto gas; but, may occasionally need to burn 100LL?

The rotax manual I have for the 912ULS says a person can run up to 25% leaded aviation fuel; but I don't remember seeing anything about what to do with the oil in this case.

In other words, is there anything wrong with running oil which is not fully synthetic all the time in the case that occasionally a person may end up using 100LL?

Sincerely,

Dave S
K7 Trigear
912ULS Warp

BTW - at least for Minnesota folks, or those who visit here, there is a listing of all gas stations which sell unleaded 92 octane auto gas. This is located on the Minnesota Street Rod Association website as a 4 page PDF. The site is www.msra.com - then click on "Features" and you will see a selection for "non-oxygenated fuel". The car folks have issues with ethanol too (not too many jokes about that now! Although, I will mention that one corn gas refinery in Benson, MN also makes a high octane Vodka on the side.)

[Mnflyer]

Hi Dave, personally I don't think occasional use will hurt anything much it takes a long time for the lead to build up, I use 100LL in my HKS occasionally, which has the same wording about 100LL and alcohol usage . One could carry a small bottle of Decalin runup in the plane and add it when fueling with 100LL or use the new Aeroshell oil developed for these type of engines. If we lose the non alcohol 91 Oct here in MN I'll go with 100LL, use Decalin and a semi syn oil but probably not the shell oil as its way overpriced in my book.

[DesertFox4]

Dave - you may run non-synthetic oil exclusively as I do. I have used Honda's Pro motorcycle oil exclusively in both my Rotax 912 & 912S equipped Kitfoxs'. Make sure you use a high grade oil which meets Rotax requirements like Honda's Pro oil and that it has the gear case additive, like Honda's Pro oil. This gives you the protection you need for both engine and gearbox and the flexibility to use 100LL Av-gas if you need to. You should use Delcolin fuel additive if running predominately 100LL Av-gas. An occasional tank of 100LL AV-gas, like you might need to use on a cross country trip, should give you no concern at all. You are not damaging your engine.

[RandyL]

"Stay away from full synthetic engine oils when running 100LL. The new Shell oil that Kitfox Aircraft LLC. now carries looks like a good choice."

I was hoping that you might consider elaborating on this piece of information. This is not a challenge but a request for help and information. Thanks

Dee

Dee,

They have found in testing that synthetics don't keep the lead that inevitably makes its way into the oil in suspension as a good detergent oil is supposed to. Rather it lets the lead deposit everywhere inside the engine. The inherent properties of petroleum oil by contrast do keep the lead from sticking and thus let it drain when you change your oil. Synthetic blends (aka "semisynthetic") provide the benefits of both and really are the proper solution for a Rotax run on 100LL. That's wy AeroShell just introduced such an oil. Mobil introduced a full synthetic into the aviation market some time ago and eventually had to take it off the market for this very reason. It is also why the two leading premium oils, Aeroshell 15w-50 and Exxon Elite 20w-50, are both semisynthetic.

As you know, because of the PSRU, motorcycle oils are a good match for the Rotax. Accordingly Honda oil has found favor with Rotax operators. They make two oils that are popular, GN4 is a conventional multi-vis petroleum, and HP4 is their semi-synthetic. Of course there are others.

[paulc]

100LL vs Auto, My 2 cents!

100LL GOODIES

• Avgas 100LL: Higher Octane ratings MON.100, RON120
• Formulated for anti detonation due to high Tetra-ethyl lead content
• Formulated for anti vapour locking at altitude
• Formulated for anti valve, guides and seat wear due to Tetra-ethyl lead content
• Formulated for high tolerance to mixture fluctuation i.e. anti fouling properties.
• Does not run “summer” and “winter” blends
• No Ethanol
• Is manufactured with tight chemical tolerances i.e. batch consistency
• Airport depots and pumps strictly check for water and other inclusions on a daily basis and sign off.

100LL BADS

• More expensive
• Not available every where
• Lead not good for planet
• Lead does not mix well with 100% synthetic oils

AUTO:GAS GOODIES:

• Readily available
• Cheaper than Avgas
• Can be used with any oil

AUTO GAS BADS:

• Not certified
• Less tank inspections for inclusions
• Low octane 85 MON, 98RON (lower number for non premium)
• Detonates earlier due to low octane number and absence of Tetra-ethyl lead.
• Vapour locks earlier due to formulation
• Winter and Summer blends
• Less tolerance to mixture fluctuation i.e. black carbon build.
• Ethanol blends destroy many plastics and rubbers
• No upper cylinder lubricants (nothing for valves, guides and seats) absence of Tetra-ethyl lead.

Learn more about octane and ratings here: http://en.wikipedia.org/wiki/Octane_rating

[kitfox812]

George

I can still get non-ethanol fuel in
Bonners Ferry at the Exon/Pacific Pride Pump. Also the Co-op in Sandpoint. There may be more down your way for the boaters near Coeur D Alene. A couple of us here use AV-9 from California Power Systems. It is advertised as a 912/914 semi syn oil with additive and buying it in two case lots comes to about $6/qt with shipping.

Rich

[mr bill]

State of Wisconsin exempts airports from requiring alcohol in the gas. Here is a list of known airports in Wi that have mogas with no alcohol. 02C, BUU, 57C, 62C, 88C, C77, C47, KHXF and KMTW. Most of them sell only premium and the prices range from $3.66 to 4.90. There are many others in Wi and IL. These are just the ones I know of.