Went to Walmart to get an oil change. I asked for mobil 1 10w/30 ep and they put in castrol syn 0w/30. I live in Houston. Is this going to hurt my engine?

 

because you live in Texas (i.e. no cold winters or snow) the 0 w 30 is fine, although typically in 'normal' climates 0w30 is used as engine flush before putting full synthetic in it. Also, if you live in Texas, don't use a 10w grade of oil, you don't even have snow, a 5w grade full synthetic is the best oil for your engine, especially a 5w20 or 5w30 oil. Anything thicker and well, I mean you do havea turbo engine don't you? If not, just stick with either of those grades, or recommended grade in the owners manual.

 

Actually because you live in Texas, 10w30 should be good enough for you because of how HOT it gets down there. Actually go with that, instead of the 0w30, but use the 0w30 as engine flush then use full synthetic oil.