Does anyone KNOW where the thought / knowledge / guess / suspicion that premixing is a better or acceptable alternative to using the OMP comes from? Has it been lab tested or is this a RX7 "wives tale" that has been passed down from generation to generation without question?

Not that I am saying it is bad - or not good advice, I just wonder where it came from.

 

I think it came from the fact that it's near impossible to tell, at a glance, if the OMP has stopped working until it's too late. Safer option, in addition to uncomplicating things further and eliminating an additional fail point, was to simply premix in with the fuel tank.

Not 100%, but that's always been my thoughts on it.

 

Yes, thanks, I understand that, my question really pertains to the thoughts that:

• 2-4 oz is enough premix
• the premix in the gas tank will make it through the fuel system to be injected... instead of just sitting on top of the gasoline in the tank
• that the premix oil will even be light enough to make it through the fuel system and past the injectors
• Since the engine normally ingests about 6 oz of "regular" motor oil per 1500-2000 miles, why is 2 stroke substituted for premix and why so much?

Stuff like that.

 

Two stroke oil is made to mix easily with gasoline and stay mixed with it, it would not be easy to seperate unless you had a centrifuge on hand.
The knowledge to use it probably comes from the two stroke engines that were around when the wankel was invented and needed lubrication in the combustion chamber.
Two stroke engines are the closest thing to a rotary, in terms of combustion cycles at least.

 

Thanks on the 2Stroke... that it stays suspended is good to know.

 

i've read many different threads like this on premixing. if u have never owned anything with a 2 stroke engine, i guess u wouldn't know. 2 stroke oil is, well, oil. and while quite thinner than motor oil, it will still settle out over time. my thinking on this stems back to when i was a kid growing up riding dirt bikes. while me and my brother's were 4 stroke, dad's had a 2 stroke. always hated riding behind him cause when he'd gun it, it would sling mud off them big knobby tires on us. but anyway, not knowing the significance of it then but knowing now, i remember every time, before riding it he would shake the bike side to side, front to back holding the front brake. agitating the fuel to remix what had settled out. don't u do this with the gas can to ur 2 stroke weedeater? i do. so when ur at the gas station filling up, make sure to shake and bounce ur car or or quick side to side shifts on the road like ur warming the tires for track day. just don't let a cop see u.

 

I've never seen it settle or separate from gasolene. Alcohol fuels might be different. And I have never seen an owners manual for any 2t engined vehicle or device that I have owned saying to shake it before use. Even if it does, I would imagine the first slosh of the tank backing out your driveway and your return lines pouring back into the tank will negate this.