My vitz 2012 is driven 162k now, and started to consume 5w-30 oil on extreme/ highway drive only. No significant oil consumption at normal speed city drive but at higher speed/ acceleration, it will consume upto 1litr/ 400km. I have noticed that it gives black smoke when above certain speed on highway or at immediate acceleration in city drive.
As a attempted remedy of oil consumption, I changed oil to Toyota 5w50, and after 100km drive I got P0303 cylinder 3 misfire code. I didn't notice any performance issue but I got engine checked up at Toyota 3s, and after multiple diagnostics (swapping plugs/coils/ injectors around) we ruled out any possibility of problem with spark plugs, coils, and fuel injectors. Fuel injectors were serviced anway. Finally a compression test was performed, cylinder 1 and 2 had 200 psi, and cylinder 3 (the one giving P0303 misfire code) had compression of 150psi. We erased the code and nothing else was done.
Immediately, I switched oil from Toyota 5w50 to Castrol 10w40 and interestingly no P0303 misfire code for next 3000 plus kms, and scan tool does not show any pending code also. No performance/ fuel average issues noticed even before or after this episode. Also noticed that this 10w40 oil does not reduce too much on highway drive like the 5w30.
Need you advice/ opinion on what is going with the engine that has a difference of 50 psi in one cylinder's compression (150psi compared to 200 psi on other cylinders) and consumes oil at highway driving conditions? Any suggestions would help..
Thank you!
@rajaatta an advice is highly appreciated
