To Group, I previously asked about break-in oil, got no responses.
So, if I don’t hear otherwise, I will use straight 30W oil for the
first 3-5 hours then switch to Mobile One synthetic, maybe 20W-50W.
Thanks. Frank clementi
Rotary engines do not require break in. Stick with Mobile one or
Idemitsu rotary engine oil. Mix 2 cycle oil with the fuel one ounce
per gallon.
Paul Lamar
French users of Citroen GS Birotor were advised using Total 20W50
Mineral Oil, and they reported good results with it, as synthetic
oils seem producing more ashes and gums, below please find a
comment in 'Rotativement votre', a French forum on RCEs, Google
translate always gives acceptable translations into English, but in
translating for example, Spanish into Dutch, the system is much less
accurate, I suppose you're aware of the anecdote of one of the first
automatic translation computers ever tested, it was given the
sentence: 'The Spirit is strong, but the flesh is weak', translated
into Russian and back, the back translation said: 'Vodka is good,
but Goulash is inedible'
SAE papers 730048, by R D Behling and E Weise; 740160, by Jh du Jeu
and B Brandone; 840237, by Marcel Gutman; 890212, by C Kappos and S
Rajan. All deal with fuel and lubricants' issues of Wankel RCEs. For
Air Cooled engines, Shell Rotella 30 was said the best, and the
contemporary Aixro engines, charge cooled rotor and liquid cooled
housings, use Mobil 1 Racing 2T.
Typically, the top housing temperature, with an Aluminum housing, at
full open throttle, 5000 rpm, in the NSU Spider Single Rotor Engine
was 300º F [150º C] (SAE paper 650722, W Froede) and 500º F [260º C]
in the plug region of housing for a 120cc Yanmar Diesel air cooled
engine (SAE paper 720466, K Yamaoka and H Tado). I suppose more data
are available in the editions of the book on Wankel engines by K
Yamamoto published by Mazda in 1969, 1971 and 1981, some are
available for download in the web.
Have a good weekend. Best regards. Salut † Jose Gros-Aymerich,
Madrid, Spain
Mobile 1 and Idemitsu form no ashes and or gums. Minerla oil breaks
down at 250 F
Mobile 1 is good to 500 F.
Paul Lamar
Where did the note from 'Rotativement votre' go? In accordance with
Jean-Luc Jentel in the forum of the abovementioned website, the
coking temp for a mineral oil is 220º C [482º F], but 270º C [518º
F] for a Synthetic oil, so if the 220º C limit is surpassed, a
Mineral oil would leave more ashes than a Synthetic one, but please
notice that in liquid cooled Wankel RCEs, housing surface temp, as
per the 1981 K Yamamoto book, with Rotor cooling, full throttle and
6000 rpm is less than 200º C [392º F], and without Rotor cooling,
below 220º C [428º F]. K Yamamoto points that no cooling is rather
desirable in some range of low rpm, some engines have a control of
the amount of cooling/lubricating oil flowing through the Rotor.
Higher Rotor surface temperatures give a lower HC emissions, and
perhaps a better SFC. The K Yamamoto data in the same book indicate
that Rotor surface temperatures are lower at around 3000 rpm (This is
the usual range of top torque and best Volumetric Efficiency (MEP)
and SFC in many Reciprocating engines), Rotor surface temperatures
never being higher than 220º C [428º F] -In the center of Rotor
Recess-. Synthetic oils are also more resistant to shear; for heat
transfer, both Mineral and Synthetic Oil do well, apart from the
higher top limit of the Synthetic oil.
There's another, less known function of Engine Lubricating Oils, that
is its ability of solving inside the Oil itself, the Combustion
residues, water one of it, and for this purpose, Synthetic Oils do
much worse. To obtain a compromise between both extremes, many types
of partly-synthetic oils are on the market. There's nothing like
experience and the measurements that can be done in a test bench, but
for a private owner the risk of damaging the engine if testing a too
audacious modification is not affordable; as a XX Century Spanish
writer said. 'For Experiments, Soda Water' -Not Champagne- Thanks for
your attention, have a good season. Best regards. Salut + Jose
Gros-Aymerich
If it was in French we don't publish French.
It is easy to check. Put a teaspoon of the oil in questions in a old
cat food can and bake it in your kitchen oven for one half hour at
500F and get back to me. Make sure the old ball and chain is out
shopping :)
We did this test over 10 years years ago and Mobil 1 was head and
shoulders above all other oils tested. Turbine oil was the only stuff
better than Mobile 1.
Paul Lamar
Great response! This is the type everybody should give.
Thanks. Salut † Jose Gros-Aymerich
Madrid, Spain
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