[Tom Vaught]

My uncles dealership used to use Pennsylvania oil called Wolfshead oil in the 1970s and many years before that.
He told me stay away from the offshore, Shell, etc) type gulf grade oils.

At one time it was a true Pennsylvania grade oil. See Below.
Then in 2009 Pennzoil was bought by a gulf manufacturer. I stopped using the stuff then.

Info on Wolfshead oil:

Wolf's Head motor oil company manufactures various weights of motor oil, synthetic oil, and other automotive fluids. The company was founded in Pennsylvania as "Pennsylvania Crude" in 1879. Presently, its company headquarters is in Tampa, Florida. The company slogans are "The Finest Of The Fine Since 1879" and "Run With The Wolf". The oil is marketed as "superior performance, but exceptional value" and has been well respected in the muscle car community. The trademark was originally registered to Pennzoil (now owned by Shell) until at least 2009.[1] The trademark is currently registered to Amalie Oil Company.

Pennzoil is just another Gulf Oil sold by Shell for at least 13 years now.

Tom V.

Glad I bought my 100 quarts when I did.