Just serviced my wifes Copen 600cc, checked the oil about a month later and the oil level has risen any ideas what it could be ?
It could be fuel dilution. If unburnt petrol gets past the piston rings and enters the crankcase, it can dilute the engine oil and cause the oil level to rise. If the oil smells strongly of petrol or feels unusually thin and runny, fuel dilution could be the cause. It could also be coolant contamination, potentially due to a head-gasket failure. If coolant is getting into the engine oil, the oil may develop a milky or creamy. You can see this under the oil filler cap or on the dipstick. Check the coolant reservoir for a low coolant level or signs of oil contamination floating on the surface. Hopefully it's just a messurement error. If the car is not on even ground, a slight incline can alters dipstick readings
Thanks for the reply, the oil does smell of petrol, although the compression is good on all cylinders could it be the injectors delivering too much fuel, if so would it mean replacing the injectors
Hi Mike, It’s difficult to say for certain. Since the compression is good, I would say a fuel delivery issue is the prime suspect. You can find the part numbers for the 0.66L Copen on this website. All you need to do is register, and it’s free to use: https://partsfan.com/daihatsu/jp/#google_vignette As a first step, you could try sending the fuel rail and injectors to a specialist for ultrasonic cleaning and flow testing.
