Hi everyone... FYI.. I worked a long time for a very large oil co. The company was always concerned about customers adding anything at all into their fuel products and if a problem occurred and additives were found in the fuel, warranty was out the window. Now, getting down to some specific details. With regards to diesel, in summer this produce is prone to develop a microbial growth if water is present. On physical inspection it will look like black slime. Condensation inside steel storage tanks is always a problem, especially for truckers and farmers who have private tanks. Water if found at the bottom of a tank must be removed otherwise this slime will grow. If fuel usage is moderate to high through these types of tanks, I would not recommend using any additives, because if something mechanical goes south in an expensive machine, fuel manufacturer warranty will be voided and I know from the experience of some who went through this, you don't want that to happen to you. Always check for water especially during summer / wet periods. Gasoline is different story. Many people story it in small containers and it can sit unused for many months. That's me today. I've an array of 5 gallon / 20 litre containers on a rural property to fuel quad bikes, generator, water pumps, chainsaws etc..... Some of this equipment is used occasionally and seasonally, so I've got the problem of the octane rating of the gasoline reducing, which will make the fuel less combustible and the device hard to start. I have a special problem with a portable Chinese made generator that prefers not to start. I've cleaned the carburetor and replaced the Chinese spark plug with NGK and the same type that fits all of our water pumps - that actually made a difference, but now I've got to do something about the fuel in this cheap piece of crap to be sure it will start when I need it. So, I've decided to use STA-BIL in all fuel that I store for our small machines. Here's another piece of information that might be helpful. Oil companies would not make gasoline containing ethanol if it wasn't regulated by governments. That should tell us something because one thing I know is our major oil co's know how to make really good gas without politicians telling them how to do it. Also, some motor manufacturers actually tell owners not to use ethanol fuels in their engines. EG: I've got a Mitsubishi Triton and inside the fuel cap is states "Use only Unleaded Fuel". That's shorthand for don't use ethanol fuels. I hope this is helpful..
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