Originally Posted by eDJ
Just some thoughts on your oil mix, assuming you're operating a 2 cycle engine.
Octane has already been discussed. So let's talk about oils. There are synthetics and I've run them in motorcycles I've owned. Read the lable before using it in a new engine. Often engines need to be broken in with mineral based oils so the rings will wear in and seal properly against the cylinder. (again this may vary with synthetic so read what they suggest) I've used synthetics that requested the motor be broken in before switching to it. Then the synthetic
can do a fine job.
Consider if you choose to use mineral based oil for your break in or just choose to use it period....to purchase a good grade with the BIA/TCW rating. It will say that right on the container somewhere.
When you operate your engine, it is best to mix fresh quantities using fresh gasoline. Why ? Gasoline manufacturers may change their formulation up to 22 times a year to compensate for climate conditions. When the fresh gas is mixed with the oil it will be at it's most potent at that time. So it's best to mix small quantities rather than a large batch to run for months. Mixing isn't all that percise so if you are close it will still work fine. I keep a two liter soda bottle and a bar tenders measure (like two cups end to end, one cup is 1 oz and the other is 1 1/2 oz) Thus I use the calculation for oz per gallon and cut that in half. That would likely be 100 miles of gas mix.
2 cycle oil is packaged in small containers for string trimmers and quarts for outboard boat motors, to gallon jugs for larger outboard use. 40:1 ratio is common with lawn and garden motors and 50:1 up to 100:1 is possible with some of the boat motors.
So this should provide you with some insights into mixing fuel. You'll have to choose whether you wish to run synthetic or mineral based (pumped out of the ground) oil. Synthetic oil is created from chemicals and is molecularly slicker & smoother than mineral based oil thus giving better lubricity. (but often it's so slick......the piston rings won't break in properly using it if your engine is brand new....and that's the argument for breaking in with mineral based oil)
Great reply. Thanks for reminding me that the gasoline manufacturers change their formulation throughout the year to compensate for climate conditions. I have some 4 month old fuel ill need to deal with.