I took my HHR in for an oil change and after I left and got to where I needed to be then looked at the paperwork. Instead of the Valvoline 5w30 I always have put in they stuck Castrol 5w20 in. What, if any, problems will this cause? Should I worry? I have a 600 mile round trip tomorrow.

 

You will be fine.

 

Why not just call them and ask them to verify what they put in ? At the least, it could be just a paperwork error, and you could actually have the correct oil installed.
Plus, by calling, if it is the wrong oil, you can at least notify them of the problem and that you will be returning to have it corrected.

 

Thousand of people have never noticed the labels and use what grampa always used, whatever that was. Don't get all worked up about it, just get the right stuff next time.

 

that's an ODD weight.
probably a typo

i've seen 5-30, 10-30, 10-40....

 

Not really an odd weight. With todays modern engines, there is a wider range of oils weights and their applications.
The days of most vehicles using the common 30w,10w40 or 20w50 were long ago.

 

I believe Honda, Toyota, Nissan use that weight in several of their models.

 

Yeah, that is also used in some Ford models too. It is legitimately Castrol 5w20 that they put in, which is not what I specified.

 

i would change it, not the filter, just drain and refill

 

There is no need to change it. It will not hurt anything.

Doesn't hurt to talk to the oil change place and let them know of their mistake but nothing will happen to the engine from running with this weight oil.

OP-
If you were using this car as a race car then it might be a problem. If you were towing a trailer during this 600 mile trip it could be a slight issue. But for your car during this time of year driving normal highway speeds you will be fine.