Hi Scotty and community! I have a 2011 Corolla, the oil cap says 0w-20, but when go the dealer to buy the parts for the oil change (it's not that expensive, maybe a little bit more than Autozone, and the dealer is closer to my home) the guys at the parts desk give me 5w-30 oil. And the same has happened for the last 2 years, when I bought the car. I haven´t really thought much about it until now. It's getting closer the time for a new oil change, I have been using a thicker oil than the oil cap says. Have I been damaging my engine? Can I go back to 0w-20? Should I stick to 5w-30? Thanks for your advice!
Use the right oil
A 5W-30 wont destroy your engine, but it will use slightly more fuel. It is recommended to use an oil according to the car's manual, both spec and viscosity.
Thicker oil can damage the VVTi in the long run. I would not use incorrect oil viscosity because the shop is closer to me.
If it were me I would buy the correct oil and do the change myself or take it to a local mechanic to do it. Then you know what is going in there. Buy a filter too.
How many miles have you put on in those 2 years? It’s certainly not good especially on modern engines, but it’s hard to say how much damage was done (if any) in 2 years. Just moving forward, go back to the original 0W-20.
Not much, about 10k miles in 2 years.