Have any of you Yblock pro's checked out this oil? Its $10.95 a quart on line and comes in 10/30 and 15/30. Its supposed to be super for pre 1973 engines and has a high zinc content. I think the site is www .joegibbsracingoil.com I would like to hear some thoughts on it if anyone is interested in checking it out. I think Sacramento Vintage Ford offers it for sale.