Mercury 135 Verado Manual page 44

IMPORTANT: Inspect oil for signs of contamination. Oil
contaminated with water will have a milky color to it; oil
contaminated with fuel will have a strong fuel smell. If
contaminated oil is noticed, have the engine checked by your
dealer.
7. Push the dipstick back in all the way.
8. Reinstall the oil fill cap hand tight.
9. Reinstall top cowl.
FUEL AND OIL
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