Vanessa, the Tomos oil injection really is a piece of junk, and should be removed. I am a professional mechanic, and Tomos owner and rider, and know what I'm talking about. I had 2 total failures on 2 brand new mopeds, made 2 years apart. I have examined this system in great detail. It is Junk. Tomos does make great mopeds, and I highly recommend them. And I agree that it doesn't seem to make sense they would build such a great moped, and put such a crappy system on them, but they do. Some people have had them last for many thousands of miles, but they are the rare exception. I know that premixing seems to be a hassle for some people ( my sister refuses to ride a moped because she refuses to touch gas or oil ). I spend all day every day soaked in it. There is no more danger of getting dirt in your fuel if you premix than if you use the oil injection system, and if you should get dirt in your fuel, all it will do is plug up the filter. Dirt in the oil injection system on the other hand will plug up your injector, and prevent your engine from getting oil, while it is still getting gas, so it keeps running without oil. But not for long. And repairing an engine that seized due to a lack of oil can be expensive. If you premix, you know that if your engine is running, it has oil. And I do recommend premixing at 40:1, regardless of what the manual says. I have an '03 ST that I have put over 14,000 trouble free miles on, it is on it's second plug, and I have cleaned the pipe once. Both were done as preventitive maintenance more than any real need, the pipe was very clean when I removed it, and the plug was fine, but I had another one, so I replaced it. So 40:1 does NOT foul plugs, and plug up exhausts. I wouldn't go much below that however. I have used everything from weedeater oil to top of the line synthetic, with no noticable difference. Remember that in a 2 stroke engine, all the oil that you mix with the gas either gets burned, or comes out the exhaust as liquid oil, so you are putting new oil in everytime you put in gas, unlike a 4 stroke, where you have oil in the crankcase, and it has to be changed. Synthetics tend to last longer in a 4 stroke,( they don't breakdown and lose their viscosity as fast) I doubt there is any real difference in a 2 stroke. My 14,000 mile Tomos still has the compression of a new engine. A stock moped engine is not highly stressed, and will last a long time if properly cared for. Peace. Jerry.