I had my es350 serviced (oil and enginer filter) in the dealer. They told me that the front timing cover is leaking. In June, I also got my car inspected and the condition was good. I just want to know if changing oil can cause timing chain cover damage?

This is a strange occurrence. I don't think one has anything to do with the other...

How many miles are on your car? It's not unheard of that timing covers, especially the gasket/s, failing earlier than expected. Changing the oil in the car has nothing to do with the timing chain cover.

2019 24500miles. it is not so much, and still under warranty. Does the warranty cover this?

yeah, it is quite strange. I just made an appointment with Lexus dealer to check

It should be covered under warranty as it's an engine issue.

Be aware there is a Technical Service Bulletin (TSB) L-SB-0002-20 Oil Leak Diagnosis and Repair which specifies what is an oil leak covered by warranty and what is an oil seep which is not covered by warranty. Pay particular attention to the requirement for warranty coverage of photographic documentation of the oil leak BEFORE the repair is made.

While one hopes the dealer's service department already knows of and follows proper procedures and documentation for oil leak warranty claims, I think it is a good idea to know of the warranty claim requirements and get some form of acknowledgement/assurance from the dealer's service department/manager of properly making an oil leak warranty claim.

Thanks. Under multi-point inspection in toyota, it says my front timing chain cover is leaking instead of seaking. Maybe they will not give you the assurance until they inspect the car by themselves.