FredG Posted June 14, 2015 Report Share Posted June 14, 2015 Threads like this are why CT Flier has become an exercise in futility. Mobil Oil has an opinion on the question of mixing synthetic oil with non-synthetic oil. See: https://mobiloil.com/en/faq/ask-our-auto-experts/questions-for-auto-experts/what-will-happen-switching-from-synthetic-motor-oil-to-conventional-oil (the text is provided, below) Q: "What will happen switching from synthetic motor oil to conventional oil?" A: "Synthetic oils typically provide better protection than conventional oils, but switching back and forth between full synthetic and conventional oil will not damage the engine. Of course, this depends on the current engine condition and the quality of the conventional oil being used." BTW, the Valvoline web site says the same thing. I stopped at these two web site. And, regarding Rotax suddenly ending its recommendation of several oils and now only recommending Aeroshell Sport 4, what is it about the 912 that makes it so different than any other engine that only one oil will work in it? It is, in fact, a pretty conventional engine. Link to comment Share on other sites More sharing options...
Roger Lee Posted June 14, 2015 Report Share Posted June 14, 2015 You got it Fred. To my knowledge that's the way it has always been. Link to comment Share on other sites More sharing options...
Anticept Posted June 14, 2015 Report Share Posted June 14, 2015 To add on: most synthetic oils come from mineral oil bases. They undergo a little extra processing. Many specifications, both military and civilian, REQUIRE that oils remain compatible if they are to state they follow "x" spec. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 15, 2015 Report Share Posted June 15, 2015 Opinions do vary, but there is no question Mobil 1 motorcycle racing oil is formulated to handle temperature and high RPM better than semi syns or other engine motor oils not formulated for the stresses of such an engine environment. And there is no question lead is an issue in the engine, Rotax agrees and admonished owners in regard to mogas versus leaded gas as well. Roger, your argument is not with Kevin, it's with the chemists that work for the oil industry. I appreciate your mechanical expertise, but I am again going with both Kevin and the chemists working for the oil industry on this one.... I am also still going with Kevin's explanation on the gear box washers and how to observe the filings on the mag plug.... And you are going *against* Rotax recommendations. Their only recommended oil at this point is the new red bottle Aeroshell Sport +4, a semi-synthetic blend. Shell and Rotax spent the better part of a decade developing that blend *entirely* for your engine and its specific requirements. You defer to "experts", but ignore the ones that put the engine together and spent the most time working on oil for it... I'm not saying that there's anything wrong with using Mobil in your engine, I'm just saying if you are going to defer to "experts", defer to the right ones with the most actual expertise. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 15, 2015 Report Share Posted June 15, 2015 He was one that said why fix it if it ain't broke. Don't know for sure, but my guess is either the split ring keeper came out of the top on the prop shaft or a better guess is a belleville washer broke. It could have been from lack of maint. or MIF or just a part failure. Don't know for sure yet. It just happened. New engine time. Why new engine? The gearbox is trashed, why is the engine wrecked? Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 15, 2015 Report Share Posted June 15, 2015 And, regarding Rotax suddenly ending its recommendation of several oils and now only recommending Aeroshell Sport 4, what is it about the 912 that makes it so different than any other engine that only one oil will work in it? It is, in fact, a pretty conventional engine. My take was that Rotax and Shell worked together to come up with a blend that would be a "best compromise" oil for the 912 series. As a result Rotax is probably acknowledging Shell's work by giving them an exclusive recommendation. I doubt it has much to do with other oils being unsuitable, and more to do with corporate politics, and also that they probably really consider this blend the best compromise that will work in the widest variety of conditions, providing the best average wear characteristics. Link to comment Share on other sites More sharing options...
gbigs Posted June 15, 2015 Report Share Posted June 15, 2015 And you are going *against* Rotax recommendations. Their only recommended oil at this point is the new red bottle Aeroshell Sport +4, a semi-synthetic blend. Shell and Rotax spent the better part of a decade developing that blend *entirely* for your engine and its specific requirements. You defer to "experts", but ignore the ones that put the engine together and spent the most time working on oil for it... I'm not saying that there's anything wrong with using Mobil in your engine, I'm just saying if you are going to defer to "experts", defer to the right ones with the most actual expertise. Not quite. Aeroshell is recommended as a semi-synthetic if you use 100LL. Mobil 1 4t racing oil is a full synthetic recommended if you use mogas exclusively. Those running 100LL are clogging their engines! So Rotax says you must change your filter and Aeroshell every 25 hours versus 50 hours for filter and Mobil 1 4t racing in a mogas run engine. Also, Rotax says gearbox and other large maint. intervals are affected by what fuel you use. Lead is not only dirty and toxic it's also bad for your Rotax engine. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted June 15, 2015 Report Share Posted June 15, 2015 My take was that Rotax and Shell worked together to come up with a blend that would be a "best compromise" oil for the 912 series. As a result Rotax is probably acknowledging Shell's work by giving them an exclusive recommendation. I doubt it has much to do with other oils being unsuitable, and more to do with corporate politics, and also that they probably really consider this blend the best compromise that will work in the widest variety of conditions, providing the best average wear characteristics. My take (the correct take) is that Rotax limited its testing / approval / monitoring to a single brand. There are too many to test them all. Rotax made things easy on themselves. Link to comment Share on other sites More sharing options...
Roger Lee Posted June 15, 2015 Report Share Posted June 15, 2015 Hi Andy, "Why new engine? The gearbox is trashed, why is the engine wrecked?" It took out the case too. look at the pictures again. The whole top part of the case is gone. that isn't part of the gearbox. It would be cost prohibitive to try and rebuild a gearbox and engine. Rotax did indeed limit their fluid testing because it would be extremely time consuming and very costly. They can't test for the world so they limit themselves to a know good product anything past that and it's up to the owner to meet the fluid spec from their regional supplies of fluids. Aero Shell's development of the Sport Plus 4 for Rotax was done for a high wear and high rev. application. This was the only reason for the last 4 years in tweaking the oil. It was done in conjunction with some high time flight schools where they could tear down engines. The base stock was tweaked and so was the additive package. No reason this oil couldn't be used in a motorcycle type application. As often as we change oil using most appropriate oils will do a good job. ( I do think there may be a few standouts) Because of our frequent oil changes I would see no advantage or disadvantage using a good semi synthetic over a full synthetic except if you were using 100LL then semi synthetic is the correct choice. Link to comment Share on other sites More sharing options...
Jim Posted June 15, 2015 Report Share Posted June 15, 2015 Amen. It's OK to have opinions, but don't post them as fact. I'm pretty sure that Hamburger can't tell the difference. Link to comment Share on other sites More sharing options...
gbigs Posted June 15, 2015 Report Share Posted June 15, 2015 Here is the Rotax Service Instruction that discusses oil for the 912 and 914. Mobil 1 is listed among the recommended types. http://204.92.52.209/aviation/pdf/ROTAX-Service-Instruction.pdf Here is a full discussion of 100LL in a Rotax. 100LL is okay to use, BUT NOT RECOMMENDED. http://www.rotaxservice.com/rotax_tips/rotax_feed4.htm Here is a Rotax Service Instruction admonishing the use of 100LL: AVGAS 100LL places greater stress on the valve seats due to its high lead content and forms increased deposits in the combustion chamber and lead sediments in the oil system. Thus it should only be used in case of problems with vapor lock or when other types of gasoline are unavailable... http://204.92.52.209/aviation/pdf/ROTAX-Service-Instruction.pdf Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 15, 2015 Report Share Posted June 15, 2015 Suggest you read the following: http://204.92.52.209/aviation/pdf/ROTAX-Service-Instruction.pdf http://www.rotaxservice.com/rotax_tips/rotax_feed4.htm You are a laugh riot. The service bulletin you posted is from 2011. Here's the new one for 2015: http://www.flyrotax.com/portaldata/5/dokus/d06038.pdf What does the updated bulletin say for BOTH 100LL and mogas? The *only* recommended oil for *any* fuel type is now Aeroshell Sport +4. Your information is four years out of date. Why do you harp that 100LL is "okay but not recommended" while using a non-recommended oil? If you want to abide by manufacturer recommendations, don't pick and choose. Either get on the train using Aeroshell or quit bleating on about 100LL. Link to comment Share on other sites More sharing options...
procharger Posted June 15, 2015 Author Report Share Posted June 15, 2015 I didn't mean to start a war, I'm going to contact my airplane lawyer so I don't get sued Link to comment Share on other sites More sharing options...
Roger Lee Posted June 15, 2015 Report Share Posted June 15, 2015 It just goes to show you shouldn't discuss politics, religion or oil. Link to comment Share on other sites More sharing options...
Top Cat Posted June 15, 2015 Report Share Posted June 15, 2015 It just goes to show you shouldn't discuss politics, religion or oil. Hey this is serious stuff! Rotax says:- "Non-compliance with these instructions could result in engine damage, serious injuries or even….(gulp)…death!" Yikes! Link to comment Share on other sites More sharing options...
ralarcon Posted June 16, 2015 Report Share Posted June 16, 2015 Hey this is serious stuff! Rotax says:- "Non-compliance with these instructions could result in engine dame, serious injuries or even….(gulp)…death!" Yikes! I'll do what Rotax recommends , then ! Cheers Link to comment Share on other sites More sharing options...
FredG Posted June 16, 2015 Report Share Posted June 16, 2015 I can't wait until Rotax decides that only one manufacturer of fuel can be recommended for the 912. Makes as much sense to me as recommending one brand of motor oil. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 16, 2015 Report Share Posted June 16, 2015 I can't wait until Rotax decides that only one manufacturer of fuel can be recommended for the 912. Makes as much sense to me as recommending one brand of motor oil. Well, tehre is "recommended" and there is "acceptable". Rotax can have a recommendation but still consider alternatives acceptable. I think that's what's happening here. Link to comment Share on other sites More sharing options...
Anticept Posted June 16, 2015 Report Share Posted June 16, 2015 I thought Rotax was publishing a spec for oil so others could get in on it if they wanted. Link to comment Share on other sites More sharing options...
FredG Posted June 17, 2015 Report Share Posted June 17, 2015 Andy, in the SI you posted earlier in this thread, Rotax made no mention of acceptable oil alternatives (that I could find). I see no basis to conclude that Rotax considers any other oil acceptable. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 17, 2015 Report Share Posted June 17, 2015 Andy, in the SI you posted earlier in this thread, Rotax made no mention of acceptable oil alternatives (that I could find). I see no basis to conclude that Rotax considers any other oil acceptable. But the document does list the Aeroshell as a "recommendation" and not a "requirement". Link to comment Share on other sites More sharing options...
Roger Lee Posted June 17, 2015 Report Share Posted June 17, 2015 It is a recommendation. Link to comment Share on other sites More sharing options...
Ian Posted June 17, 2015 Report Share Posted June 17, 2015 Just as a matter of interest and probably apropos of very little - there's been a discussion of engine oil over on the Pilot Prune forum http://www.pprune.org/private-flying/562916-engine-oils.html Link to comment Share on other sites More sharing options...
FredG Posted June 17, 2015 Report Share Posted June 17, 2015 Rotax does not make its guidance on oil selection especially clear or useful. From the SI, "Use only oil which is classified by ROTAX standard (RON)!" (Section 3.1) While the word "only" seems to leave little room for discretion, they do use the word "recommended" elsewhere. Do we know of any oil other than AeroShell Sport Plus 4 that is classified by the ROTAX standard (RON 424)? I do not. We can call it a "recommendation" all we want, but the SI does not name a single other oil that is acceptable. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted June 17, 2015 Report Share Posted June 17, 2015 Just as a matter of interest and probably apropos of very little - there's been a discussion of engine oil over on the Pilot Prune forum http://www.pprune.org/private-flying/562916-engine-oils.html They seem to have come to the same conclusions we have. Meaning: none. Link to comment Share on other sites More sharing options...
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