Motor oil problem, unsure how to proceed

Hello,

OK, my 2007 Prius (bought in 2017) has been doing great for the most part, still on the original hybrid battery.

About a month ago, I noticed it was making beeping noises and flashing the word "Problem" on the screen whenever I turned a sharp corner. I thought my oil might be getting low, so I took it to a nearby mechanic (my regular mechanic is several miles away), who plugged it into the diagnostic thingy and said all looked fine but yes, my oil was a bit low so he topped me off. And he didn't even charge me anything! The beeping noise went away.

Until a few days ago. I was making a sharp turn and it happened again. I thought, dang, the car has developed an oil leak. A few moments later, it happened again when I hit the brake (not hard) at a stoplight. I got the red triangle, just for a moment.

Yesterday it happened again, just once when I hit the brake at a stop sign. Today I decided to check the oil level myself to see if that might be the problem. When I popped open the hood I was shocked to discover the cap for the oil compartment was off. The mechanic who topped off my oil had left the cap up on the little shelf next to the windshield wipers. When I tried to read the oil level using the dipstick, I couldn't find ANYTHING. I tried twice.

I tried several times to call the nearby mechanic, but they're not answering the phone right now. I called my regular mechanic, who said it's too dangerous for me to drive my car all the way to their location. There's a Walmart supercenter about a mile away from me; he said I could drive there and buy some oil and put it in myself, and he gave me some advice on how to do that.

It also occurs to me I could order the motor oil from Walmart and have it delivered to my house. Which seems like the best plan, but I am unsure what type to get. My regular mechanic said they always use 5w-20 when they do my oil changes (he triple-checked this), but Toyota says I should use 5w-30. And I don't know what type of oil the other mechanic used to top off the oil last month. I'm seeing conflicting advice about whether or not it's OK to mix 5w-20 and 5w-30 in a Prius.

I am not a mechanically-minded person, and this will be my first time adding motor oil to the car myself. I just don't want to screw it up and do anything that would damage the car any more than it already has been. What should I do? Any advice is greatly appreciated.

 

Will do. Thank you so much!

 

Yes. As I mentioned in my post, I tried twice to measure the oil with the dipstick, and could not find any reading of oil in the tank. But thanks for the suggestion.