An oil base skin care composition including squalane and a method for treating skin are disclosed. The method includes the step of individually displaying a plurality of visual skin guides to a consumer. Each of the visual skin guides includes a plurality of visual representations of a categorical skin condition. Each of the visual representations correspond to a severity score for the categorical skin condition on the visual skin guide. The method further includes correlating the severity score for each of the categorical skin conditions for each of the visual skin guides to the consumer's current skin condition. At least two target skin conditions from the plurality of categorical skin conditions are determined in response to the severity scores for each of the categorical skin conditions. At least one booster containing at least one active ingredient is correlated for treating each target skin condition.