Can't find Castrol HD 30 wt for the last few months at Autozone, Pep Boys, or O'Reilly. They used to always have it. Anyone know what happened? Been using that in the summer for a while, figured it's good for long high speed trips where it's 110-115 F in the shade all day. I put 10W-30 in the winter but it's still hot.

According to their web page Walmart and Tractor Supply have it in my area for a little less than $5 a quart.