Before Chevron bought Texaco, Texaco and Shell had put their lubricants business into a joint venture called Equilon. The FTC insisted that Chevron get a divorce from Equilon after the purchase of Texaco. I believe that Equilon went all back into Shell's hands and is now part of SOPUS (Shell Oil Products US). SOPUS markets lubricants under the Shell, Quaker State, Pennzoil and other brands.
Havoline is now a product of Chevron Lubricants.
All that said, the old Havoline Synthetic was a good oil in it's day. I still have some left over from my clearance sale binges and use it without worries.