Anymore, I've been using Walmart 10w-30 for the old cars. It's cheap, I think the last 5 gt. jug I bought was like $17-$18. I don't like the idea of synthetics in these old cars I don't think it is needed plus it will leak out of the seals more easily.
I only put maybe 200-250 miles per year on our old cars, and can't justify using Mobil 1 and other expensive motor oils.
Look it up, Walmart motor oils are refined by the Warren Oil Company and they have some good products. A mechanic told me years ago at that time it was made by Mobil that is why it is in a blue bottle.
Time will tell!