I forgot to tell my wife to pick up 5W30 for my last oil change and they gave her 10W30 instead. It is Mobile 1 extended. I knew better but was in a hurry. Can I thin it with ATF or should I start over using the right stuff? The head is starting to rattle a bit especially when cold. 2000 Metro, Auto, 160,000 miles, runs strong. Thanks for any and all replies.

don't mix it, atf is made for different purpose than motor oil and has other additives in it

yeah, i'll agree, it's not recommended.