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Up Topic Algemeen / RX-8 discussie / who premixes there fuel and what oil do you use with what ratio
- By paddy187 (Deelnemer) [nl] Date 29-06-2012 20:10

Just was wondering what the general consensus on this forum about pre-mixing with 2 stroke oil? so if so what oil do you prefer and what ratio.
- By Faxie (Rotary SuperSpammer) [nl] Date 29-06-2012 20:14
I'm not premixing, HP and 130000 km with no problems whatsoever.

I think that for normal use the standard oil injection on the Renesis would be sufficient.

Premixing won't do any harm though, on the contrary.
- By rudolphw (Rotary SuperSpammer) [nl] Date 29-06-2012 22:02 Edited 29-06-2012 22:28
I premix 300ml 2 stroke oil per tankfill of 45 litres  {MPM 2-Stroke Oil Synthetic TC+.........CEC/API:TC+; ISO-L-EGD; JASO FC (low smoke); Piaggio SI; TISI}

This is a personal choice based upon the undermentioned:

When using 2 stroke oil with the Sohn Adapter (the std. OMP does not supply 4 stroke oil anymore in that case) Sohn's advice for the quantity of 2 stroke oil that have to be used is 1:100 (this is 10 ml 2 stroke oil per 1000 ml fuel)
(Sohn states: The Oil Metering Pump (OMP) Adapter, manufactured by Richard Sohn, takes the solution one step further by allowing the use of the stock metering pump, but supplying it with two-stroke oil./Oil consumption is approximately 1/100 of fuel used.)

The std. engine oil consumption via the OMP of the RX is generally approx. 1 litre 4 stroke oil per 3500 km, which requires approx. 400 litres of gasoline.
The consumption of the std. OMP therefore is approx 2,5 ml 4 stroke oil per 1000 ml fuel. (ratio 1:250)
My personal opinion is that to match with the ratio as applied with the Sohn Adapter I will have to supply additionally 7,5 ml of 2 stroke oil for each 1000 ml of fuel (ratio 1:133).
With this total of 10 ml oil (2 stroke plus 4 stroke) for 1000 ml fuel the ratio is 1:100.
With a 45 litres fuel fillup 7,5x45=approx 300-340 ml 2 stroke oil is added.

Seven reasons as a motivation for my personal choice for a ratio of 1:100 are:
1) The advice of Richard Sohn
2) Aviation rotaries (running however at constant 6000 rpm/without OMP) are premixed with a ratio of 1:80 (manufacturer's recommendation)
3) Rotaryexperts in the USA since long advise the use of 1/2 us oz (custom use/with OMP) or 1/1 us oz (evt without OMP/racing/trackdays) 2 stroke per 1 us gallon fuel (resp. ratios 1:256 and 1:128). They report that carbon deposits are minimal compared with non-premixed engines.
.........herewith a picture of a rotor from a premixed engine after 75.000 km............
.........and here a picture of a rotor from a non-premixed engine after 80.000 km........
4) Old RX 7 rotaries using 1/1 us oz 2 stroke per 1 us gallon fuel achieved amazing lifetimes of over 100-200.000 miles
5) The rotary engine is unique in its design, however comparison with lubrication conditions for the combustion area of any other engine tends me to
compare it with the well known 2 stroke engine which generally premix with a ratio of 1:25-50 (chainsaws, lawnmowers, karts, scooters, motorbikes) or 1:50-100 (motorbikes, marine outboards)
6) Premixing is a safety measure in case the (relatively unreliable) OMP and/or OMP lines which are easily clogged are not working as required/not at all, due to several reasons.
7) Premixing does in principle not affect the lifetime/function of your catalytic converter and is not clogging the filter of the fuel pump. (These info's are from the USA forum and rotary experts) 

About premix (yes/no/which ratio/which oil/with or without Sohn adapter/etc) discussions generally never end (see USA-Forum:   140 pages!!!; therefore above my personal opinion to those who are interested to read this; however i will not enter into any discussion (please do not misunderstand me).........

Regards, Ruud
- By Dennis (Rotary SuperSpammer) [nl] Date 01-07-2012 19:23
Carbon deposites are often build up by using the engine the wrong way.
It should rev to burn away all of the carbon deposites.

Where are the pics of the start of the experiment?
Were both engines new?
Were the engines treated exactly the same way, by what temp, load, conditions etc.?
When you state something be sure it's backed up by data, before, during and at the end of the experiment (let's say this was a real experiment with proper conclusions).
And even more important to draw ANY conclusions: can you reproduce the outcome?

Personally, I THINK this small amount of oil won't make any difference, either 4 or 2 stroke.
All oil contain additives but they are present in such a small amount (even less in a 1/100 solution) it wouldn't make any difference in building up more or less deposites.
You can help the completion of burning by adding more heat, it will burn all but still, it will NEVER burn clean!
That goes for both kinds, nothing more, nothing less.

So, do what you want or what feels right, there is no proof as there is no real NULL TEST, a Rotary dies sooner or later if you want it or not, that's a fact not an assumption.

Don't get me wrong, these machines are just awsome and i trust Mazda's engineers, even by knowing it won't last forever...
I enjoy every mile.

Grtz Dennis.
- By rudolphw (Rotary SuperSpammer) [nl] Date 04-07-2012 21:02

> Folks,
> Just was wondering what the general consensus on
> this forum about pre-mixing with 2 stroke oil? so
> if so what oil do you prefer and what ratio.

What's your opinion?
- By paddy187 (Deelnemer) [nl] Date 11-07-2012 19:06
I am going to premix with 2 stroke with about 250mL-300mL per tank and see what happens in feel and fuel useage.
- By rudolphw (Rotary SuperSpammer) [nl] Date 11-07-2012 19:27
Good idea....
Thanks for info.......
Regards, Ruud
- By Dennis (Rotary SuperSpammer) [nl] Date 09-08-2012 05:40
Premixing only adds more oil and therefore more carbon deposites.

Btw, title of your topic: "there"??? I think you mean "their".
Common mistake made by native english!

Grtz Dee.
- By Bartman (ForumGeweldenaar) [be] Date 09-08-2012 07:41

- By Dennis (Rotary SuperSpammer) [nl] Date 09-08-2012 07:59

> :-)

Dad's what eye sad. :-)

Grtz Dee.
- By mluyben (SuperForumposter) [nl] Date 09-08-2012 08:11
Not True! It all depends on what 2 stroke oil you use.
I have driven 2 stroke bikes half of my adult life and with the correct oil you get NO carbon deposits.
With crappy/cheap scooter oil you DO get carbon.
Use a good synthetic 2 stroke oil for high rev purposes (Kart/Race) and the oil will not leave any carbon, it will even cleanup carbon.
The high rev oils are not needed for the RX8 but they are far superior in creating an oil film to the normal (low smoke) oils.
I use Motul800, 200-250ml on a full tank. Idumitsu 2 stroke is even used by Mazda themselfs.
Revving the engine will certainly help to burn the carbon away.
The R3 has an extra oil injector, like the RX7 and that is done because?? Correct! not enough oil on the right places with 2 injectors!
2 stroke oils are far superior in creating an oil film in a combustion chambers and without leaving carbon.
That is why a lot of engine tuners/rebuilders use or recommend a Sohn adapter, no more 4 stroke oil in the rotor chamber.

- By Dennis (Rotary SuperSpammer) [nl] Date 09-08-2012 08:35
A 2-stroke piston engine is not a rotary engine and because of the shape of the combustion chamber of a rotary, it will never burn clean.
Hence the extra double fireing trailing spark plugs.
This has and will always be a problem with rotary engines.
Ever seen a clean exhaust muffler on a rotary engine?

Grtz Dee.
- By mluyben (SuperForumposter) [nl] Date 09-08-2012 12:46
True it is not a piston engine, so there will always be issues with the flamefront and such..
Burning the heavy 4 stroke oil will leave a nice tarmac layar in your exhaust, almost like cheap 2 stroke will (although always less then 4stroke).
All I want to point out is that it is not always true that premixing will give you more carbon deposits.
Using good 2 stroke oil will leave a nice grey and dry exhaust on a 2 stroke piston motor. On a pre R3 engine it will not hurt your engine to use premix.
On an R3 engine it will probably be pointless to add premix.

So in short, are you willing to pay for premium 2 stroke then go ahead. If not, then stay away from premix. It will clog up your cat, engine and exhaust.
Is this better Dennis?

- By Dennis (Rotary SuperSpammer) [nl] Date 09-08-2012 17:21
I agree to disagree. :-)
I don't have a cat to start with.
Second, why all the hussle to prevent carbon deposites?
I know, seals could stuck but then you don't have used the engine the right way, they don't stuck just like that, they move a lot you know...
Glowing carbon can do strange things to ignition cycles but that's a rare occasion in a n/a rotary.
It's more likely a coil will fail and THAT should be the main concern.
If the trailing fails you will get a lot of carbon deposites, no matter if you use 2-stroke or 4-stroke.
Check them periodicly and you are fine, rev it from time to time, it's build to perform.

The seals on the other hand WILL wear out, it's just a matter of time.
I don't care if it brakes down with a "clean" or a dirty rotor imho...
If you don't want this to happen, rebuild the engine after 100.000km's.

Besides, if it was THE trick to expand the lifetime of a production rotary, why isn't Mazda using this miraculous invention?
I believe it doesn't make a huge difference in terms of lifetime but i agree it burns cleaner.

Grtz Dennis
- By roy (Powerposter) [nl] Date 02-02-2013 20:40 Edited 02-02-2013 20:42
I use Castrol power rs tts 2t oil in combo with a sohn adapter so a extra oil reservoir needed, but i like it no more 4 stroke oil entering the combustion chamber but only quality 2 stroke oil.
I haven't opened the motor but i changed the exhaust manifold about 2 months ago and looking into the exhaust ports it  looked nice light grey collared and clean no black shit ore whatever .... but like mentioned before be sure your coils and spark plugs are fine.


Up Topic Algemeen / RX-8 discussie / who premixes there fuel and what oil do you use with what ratio

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