they want use warranty void as threaten to earn the kawkaw marked up price from u

conduct the forensic report by professional to prove that engine oil is the cause of part failure so can exempted from warranty responsibility
not just assuming by doing that 'could' damage the part so dont need honour the warranty

sc should pay to conduct this report in case they feel suspicious, they should honour the warranty for buyer, innocence until proven guilty
just proceed warranty process if dont want pay for the investigation, and not just simply accusing oh because he/she not follow maintenance schedule or this modification 'might' damaging the parts

inb4 forgot laws made to protect helang