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The fuel/oil ratios displayed in column E are baseline values that vary depending on the engine data you will enter. Data entry cells are colored light blue. The needed variables for determining the ratio are the calculated upper cylinder temp and oil viscosity at that temp. Column G displays the oil cost per gallon or liter of gasoline at the displayed fuel/oil ratios. Only the oils that are acceptable for your engine have their costs displayed. Since oil costs vary in different countries the spreadsheet allows you to change its cost per liter in column L. If you only have its cost per quart then multiply that by 1.05 to get the cost per liter. Prices are in USD. Only oils with less than 40% group 1 oil are acceptable for engines with power valves because group 1 oil burns too dirty. Only oils with a viscosity index of 120 or more are acceptable for engines that aren't used mostly at high RPM. There are 24 more engine oils in the calculator than what is seen from this screenshot:  The ratios displayed are baseline which means you can vary from it although I would discourage anyone from using much less oil than the baseline. I'd prefer people using even more oil for more protection. All air cooled engines should use a low ratio so that there is enough oil presence to cushion piston slap when the engine isn't running hot at high RPM. Below you can see that the spreadsheet has 4 spaces for 4 other oils that you can enter if you know their specs (150C + 200C viscosity). The resultant recommended fuel/oil ratio will display in column E.  |