As most of you know, winter blend auto gas has a different RVP than summer blend. This can be critical in the Rotax 912 ULS engine and can cause vapor lock. Some RV12 pilots have experienced this. Summer blend auto fuel RVP is less susceptible to vapor lock, so I try to stock up a little extra summer blend when I can. I just read that winter blend will begin to roll out on Sept 15 here in Kentucky so I filled my spare 55 gal drum, which gives me close to an extra 15 hours of peace of mind. I do buy ethanol free auto fuel, which I understand has a slightly longer shelf life. You may want to check for the date in your area and stock up a little extra Summer Blend if you can. Just my opinion…. Tom.
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Winter vs Summer Blend Auto Fuel.
- Thread starter todehnal
- Start date
Checking for product changeover dates is indeed very important, but is often easier said than done. Around here, the availability of people who can answer that question varies widely from convenience store chain to convenience store chain. I don't worry about this stuff with airplane fuel but I've been this route on winter diesel fuel changeover, which of course is sustantially less critical. Store managers around here are pretty clueless on the issue, but with some persistence one can usually get the name and number of the right guy at "corporate". With some additonal persistence he or she will usually, eventually, return your call.
The next challenge is "can you trust the information that they give you?"
Not much of a challenge. The answer is easy - "no".
The issue of determining whether the automotive gasoline one has purchased is winter fuel or summer fuel or a mixture is challenging.
Hopefully I was able to attach the picture of news article that described the EPA allowing winter fuel to be sold in the Midwest this summer due an Exxon Mobil refinery in Joliet Illinois being shutdown due to an earlier power outage.
Just when one thinks that they understand the rules around automotive gasoline, they change.
Brett H
Columbus, IN
N4BH
Attachments
Experimental, so you can practice whatever alchemy you want.
If one is following Rotax guidelines, you might as well just run 100LL. The decalin is not recommended. With 50% leaded operation you are in the more aggressive maintenance intervals. None of this mixing of fuels and additives accomplishes anything.
Rotax Service Instruction at 5.2) AVGAS Fuel Additives says:
"Additives under the names of Decalin® and Alcor TCP®, which aid the scavenging of lead deposits have not been tested by BRP-Rotax. Field experience shows that these products have no detrimental effect on the engine, when used in the recommended manner. Always follow the additive manufacturers instructions especially with regard to health and safety precautions. BRP-Rotax only has field experience with Decalin Runup® and Alcor TCP® brands. Other similar additives are not recommended as BRP-Rotax cannot comment on their suitability for the 912 i, 912 and 914 Series engine types."
"Additives under the names of Decalin® and Alcor TCP®, which aid the scavenging of lead deposits have not been tested by BRP-Rotax. Field experience shows that these products have no detrimental effect on the engine, when used in the recommended manner. Always follow the additive manufacturers instructions especially with regard to health and safety precautions. BRP-Rotax only has field experience with Decalin Runup® and Alcor TCP® brands. Other similar additives are not recommended as BRP-Rotax cannot comment on their suitability for the 912 i, 912 and 914 Series engine types."
Right, so they have done some testing and there is no detrimental effect. They don't make a recommendation to use it with leaded fuel, just a statement that it's not going to hurt. This is all I meant by not recommended.
I also meant that there is no benefit with respect to the maintenance schedule. The use of a lead scavenging additive is not a factor in the maintenance schedule relative to the use of leaded fuels. We can put it in to feel good, but at least according to Rotax should still do oil changes twice as often and gearbox inspection sooner.
Switching to 100LL for the shoulder period in areas where you feel the blend is unreliable is a good way to avoid the vapor lock issue. I would encourage just making a change for a few weeks/months and do an oil change over experimenting with fuel and additive blends.
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Yes. There is actually a great presentation by Ron Singh on the subject. As you point out, Van's has provided guidelines on how to manage this issue.
I have not personally had to be overly concerned being in Ca where we have extended summer blend periods and frequent turnover at most gas stations, but others in the RV-12is world operate under conditions where they could still get bit.
rpigeek
Active Member
So far on the -12 I haven’t had an issue yet with pump gas in the Bay Area. We’ll see once we get winter blend, or the worst is winter blend after it heats up in May. I’ve fought this on another Rotax airplane I have that took a lot of experimentation to eliminate the vapor lock.
