2010 - Dealer oil change. Can I top up (mix) with Mobil 1?

how much are you topping up between changes? it might be time for a heavier oil. i would stick with the same oil for topping.
however, i'm not sure what you buy in quarts from them is the same as the junk they pump out of the 55 gallon drums.

 

Yes, it would be fine. However, as long as the oil level is between the two marks on the dipstick, you don't really have to "top it up".

 

hopefully.

 

I'd second @bisco 's question: how's the oil consumption?

Any 0W20 will be fine. For a paradigm shift: pick up a bottle of Toyota 0W20? It's good stuff, all I ever use. Very cheap through dealership up here.

 

Assuming the dealer is using Toyota 0w-20 synthetic, it is blended by Mobil 1 to Toyota spec and is quite closely related to Mobil 1 AFE 0w-20. In this case you would be topping with very compatible oil. But as others have said, so long as the dealer is using a syn 0w-20, the mix won't be a problem regardless. If the dealer is cheating by using bulk, conventional 5w-30 oil, I'd (my opinion only) feel like you're improving it with M1 top-offs.

If you're not into DIY oil changes, just bring your M1 to your selected oil change place and have them use it. It is a fantastic 0w-20, always returning great used oil analysis reports.

Although the dipstick obviously gives a safe range for oil level, with these small sump engines I feel better keeping the level close to, if not at the full dot. Again, just personal opinion, as the oil discussions always are...

 

No problems at all topping it off with the M1.
As mentioned above sometimes M1=Toyota's blend, depending on who the lowest bidder is at the time.