Lets start a comprehensive thread on premix that will hopefully answer all the questions. Please add to this, and rate it so it can get archived.


Premix - mixing oil in with your gas in addition to, or as a replacement for, the oil injected by the OMP. If you do not use the premix, 1 oz per gallon works out perfectly. Its a little more oil rich than the OMP at full throttle, but not enough to make your car smoke or foul plugs quickly. 1 oz per gallon works out to a 128:1 mix of oil to gas. The OMP at full throttle gives a ratio of about 150:1. If you want to use it in addition to the OMP, just as an extra precaution against OMP failure, or for the extra compression, use 1 oz per 2 gallons of gas.

Pros
- 2 stroke oil was designed to burn, engine oil was not. Also, premix burns clean oil, while the OMP injects dirty engine oil.
- raises the compression some, especially on old or worn engines. It makes the apex seals seal better, which increases the compression by reducing blow-by.
- if you still have a functional OMP, it gives a "safety blanket" against OMP failure. While it rarely happens, it can easily take out the engien if it does. The 89-91 n/a's seem to have somewhat problematic OMP's. I have had 2 fail on me, and both killed the engine.

Cons
- the hassle of having to add oil EVERY time you put gas in your tank
- Ive noticed that I need to run a bottle of fuel injector cleaner every few months. The oil in the gas seems to make them get dirty quickly, and will cause hesitation problems. Fuel filter life is also reduced, but I am not sure by how much.

Some people may say it fouls the plugs quicker, but it has never done this on my car. I pull my plugs once a week, and they have never been fouled. I have been using premix for over 10K miles.

For more info about disabling the OMP, and some other OMP related stuff, click here

 

i guess i can't really add any know-how, but i try to put in about 1/2 oz per gallon when i fill up. sorta eases my peace of mind

 

^bump^

 

Will the premix affect the spray pattern of the fuel injectors? And how is 16oz of premix in a full tank of gas going to be evenly blended/distributed in there; wouldn't it just settle or collect on the the bottom of the tank being that it (may) be heavier than gasoline? Please enlighten.

 

correct me if I am wrong, but 2-stroke oil is supposed to mix with gasoline... it will not settle out.

once it is mixed it will stay mixed, like a solution

as far as fuel system. i would not be worried bout the spray pattern of injectors. like mazdaspeed said, more fuel system cleaner and fuel filter changing than usual

 

The oil doesnt affect the viscosity of the gas enough to affect the spray pattern. Oil and gas mix very readily on their own. The oil will be completely dissolved in the gas by the time you pull out of the gas station.

 

I use premix only becuase when i bought the car they guy already had premix running. I like it personally, it kinda give me peace of mind knowing I wont be reliying on a omp for use because i am doing it myself, you dont have any garantee that your omp will last you down the street or cross country, well unless its new. The only problem i have is, it kinda runs rich when i first start but thats about all. other than that i love it.

Also as i have said before it dosent take more than 30 seconds to pour the oil in the tank.... if thats too much your just damn lazy.


All you premixers can you post your brand that you use, just to get some pros and cons of the different types where using...

 

I didn't see it mentioned, so...

The 2-stroke oil should meet the TCW-III specification (ashless). Theoretically, any oil that meets the spec will burn cleanly.

 

Fuel/oil mixtures should be shaken to encourage the mixture. Dumping it in the tank and driving around the block should be sufficient. The oils WILL seperate from the fuel with time however. Those that only drive their cars during the warm months should be aware of this. I just had to throw away about 10 gallons of race gas and premix because it had seperated. It had set for several months with stabilizer in it.

My personal choice for premix is AMSOIL. Have used it for years in 2-strokes and it provides excellent protection and very minimal deposits. About any name brand synthetic should provide both of these qualities though. Petroleum based oils would rank next IMO. Beware of bean/castor oils. They provide good protection and smell great. But they do leave heavy deposits that are mostly only a PITA with a 2-stroke because they're so easy to clean but could really foul up a rotary.

Chris