Pre-mixed oil in petrol

[andrewrx7]

Was looking on some of the US forums, and came across a thread about premixing oil into the petrol as a means of eliminating the OMP.
There were also some pics put up by a builder, I think, who reckoned the OMP did not do a very good job, and that the oil injected was not dispersed very efficiently at all - causing poor seal lubrication. He was a strong advocate (along with many others, as far as I can tell) of putting clean oil straight into the petrol tank at every fill. That way you guarentee even and continuous seal lubrication.

Anyone got any thoughts on this? Or even doing this? Is the OMP/injection system as bad as they were trying to make out? It seems quite a popular mod to remove the OMP completely and just run with a premix. Is this just for seriously modded cars etc, or would normal, less stressed rotaries benefit from this approach?

Cheers!

[RE:Worx]

*Max hat on, not REWorx one*

Quite a few rotaries over here are running premix, including myself.

It\'s good - once you get over the stigma of having to add 2 stroke oil when you fill up!

2 Stroke oils are designed to do the job that you are asking of regular oil going through the OMP and into the chamber, but burns much cleaner than regular oil.

That has to be better for the engine, also means the engine oil level never drops between oil changes.

I run at about 100:1, which is normally around half a litre a tank fill.

I\'d recommend it as a modification, but bear in mind that you may want to put it back to stock if you ever sell it! Stigma again

Some people keep the OMP and jets, but run a seperate resevoir of 2 stroke to supply it.

Max

[andrewrx7]

Ta for the reply.

2 things:
would normal (unmodded) cars benefit from this?

and do you disable the OMP system if you do run premix? One of the comments I read was that people leave the OMP operational, as a back up incase you forget to add the premix. That means you\'ll be burning both 2-stroke and the oil the OMP injects? Good/bad or not a problem?

Cheers!

[asp]

do u think it would be a good idea doin this on a low comp engine.
it could help the engine last a little longer.

[kev-yorks]

My Cosmos running premix no problems once your used to mixing when you fill. It certainly wont do you any harm if youve got low compression. Other advantages are you can give it a bit extra if your going on the track 80:1 and you can run the engine on a decent synthetic or semi synthetic oil without risking gumming your seals.
Regards Kevin

[Paul-Tll]

mmmm way to go, give your turbo(s) the oil they really deserve!
Paul..

[88GT-R]

Hi all,
I premix at a ratio of 150:1 ie, 200ml to 30ltr of fuel. If you have an FD or S5 FC on the std ecu, the omp will have to remain connected, or else the ecu will go into limp mode.
Be careful what synthetic engine oil you use(if changing to synthetic), as it will either shrink or expand the oil control rings. Motul V300 range is ideal, as the ingredients counter act each charactaristic.(shrinking and expanding)

John

[ro284]

Interesting thread! but i am wondering if adding premix will upset ron, or rather the fuel rating which may then risk causing problems especially if only 95 unleaded is availiable, more thoughts please, also which make premix is considered best please,
Thanks Bob

[kev-yorks]

shouldn\'t make any differance to the RON rating as there\'s going to be oil in the mix anyway via the metering pump. But with premix its going to be oil designed to burn clean not old stuff thats been swilling about your sump for a while. As for type i use shell semi synthetic two stroke mainly because i\'m lazy and i can get it when getting optimax. On a number of occasions i\'ve run normal 95RON with premix at 100:1 with no problems at all.Your best place for info on this topic is probably Ausrotary as there\'s loads of posts on premix ratio\'s and oil types. One tuner over there rave\'s about Still chainsaw premix oil, cheap and blended for high reving engines. If you read his posts he\'s been using it in high HP engines now for 10 years or so with no problems.
Kevin

[Spotlamp]

Is there any chance of messing up the fuel filter by running 2 stroke through it?

H

[RotorHeid]

Yes, It will mess up the filter, need change often.

Famous Jim Mederer says,use a synthetic oil for premix because mineral oils settle out of fuel if it(the mixture) sits for very long. Best choice is a two stroke synthetic which is a good lubricant and it stays in suspension.
However. he uses mineral oil exclusively and is totally pleased with the results.
Say that synthetic oil does\'t burn,so it will not have the same affect on reducing fuel octane as does mineral oil.
Synth oil also tead to leave the spark plugs with more of a residue,thus leading to fouling.
Excellent life out of the seals.( using carbon apex seals)
Also says For street engine:- keep the pump and For racing:-go pre-mix.
Hope it\'s help.
Regards
Ian

[Carl]

in most race cars that Jim is talking about that info applied to cars about 20 years ago.
I say use a mineral as when the engine is running the fuel returns to the fuel tank and keeps the mineral from settling out of the fuel by mixing it,it is cheaper too.
You can use a synthetic too,I have done for some time with no particularly bad things happening,but from using both I would recommend mineral.
As for octane being dropped it would be negligable,if you add say 125 to 1 of ratio of petrol to oil you actually have added less than 1% of oil,that means that you have only reduced the amount of fuel going into the engine by less than 1%.How can this severly reduce the octane?Pump fuel can vary much more than that just by variations in the manufacturing process,some by as much as being only around 95 octane rating when they should be 98.It pays to go to a busy service station to where petrol does not get old and loses some of its quality.
Regards
Carl

[RotorHeid]

Carl,
how about using good old stuff called "Castor R40 ",

"I love the smell of Castor R in the morning....Smells like....Rotary!"
Regards
Ian

[LeeHall]

Sorry guys, I\'m still trying to learn more about my rotary and I\'m abit thick lol. TBH, this thread has confused me abit. Could someone give me a simple straight forward answer please? Should I be putting 2 stroke oil in my FD? What type and what amounts roughly?
My cars pretty much standard (exhaust, filters and a pfc and de-cat comming soon). Its not used every day and only road use (though on occasion, fast road use lol).

Thanks and appologies again for not getting to grips with this.

Lee

[kev-yorks]

If your still running the metering pump then no you don\'t need to. If like myself your running a aftermarket ecu that doesn\'t suppport the metering pump then you don\'t have any choice in the matter we dissable/remove the pump and run premix in the fuel.
 If you check the sites in Aus and the USA you will find that quite a number of high hp motors are set up for running premix even if there ecu\'s support the metering pump because engine life/reliability is improved with premix. So its a case of what your running and personal choice