My phone does a lot more for me these days than it used to. Today, it just got that much more useful in helping me enjoy my vintage SAABs and our Lambretta scooter with two-stroke engines.

I found an app from Red Pine Media called "Premix Calculator". It is as simple as it gets and that's just perfect for me. Two sliders let you select the amount of fuel and your desired premix ratio.  It then tells you how much oil to add in either ounces or cups.

Get it for your iPhone on iTunes