CT200h Oil Contamination

Oil contamination in a hybrid like yours is tricky. The engine cycles on and off, which can lead to moisture buildup and fuel dilution in the oil, especially if your maintenance intervals are stretched. Think of it like condensation in a glass of iced tea on a hot day. Are you using the correct oil type and viscosity as specified in the Lexus manual? Have you noticed any unusual engine noises or smells, or checked for any visible oil leaks?

I'm using the oil type recommended in the manual, but I've been adding an oil additive the last couple of changes. Could that be making it worse? I didn't notice any leaks, but didn't specifically check it either.

Adding an oil additive could potentially exacerbate the problem. Some additives can react negatively with the detergents and other additives already present in the oil, leading to sludge formation and reduced oil flow. It's like mixing different paint colors – sometimes you get a nice shade, but often you end up with a muddy mess. Given the warning lights and your mileage, and the additive, I'd suggest a visit to a workshop for a thorough inspection to prevent potential engine damage.

Thanks for the advice. Took it to the shop, and you were spot on - maintenance interval exceeded, oil was indeed contaminated. New oil and filter, cost 165€. Lesson learned about those additives!