Position rack in center of oven and preheat to 180 degrees C. Generously butter rectangular metal loaf pan.
Combine syrup, yogurt, eggs, sugar, vanilla and lemon zest. Stir or whisk to combine. In a separate bowl, combine flour, baking powder and salt. Add to wet ingredients and stir to incorporate. Add oil, and fold gradually until oil absorbs into the batter.
Pour batter into prepared loaf pan. Place pan on baking sheet in oven and bake until tester inserted into centre comes out clean, about 50 minutes. Cool cake in pan on rack 5 minutes. Cut around pan sides to loosen cake. Turn cake out onto rack. Turn cake upright on rack and cool completely.