Questiondo you recommend HD oil?
AnswerThe choice of oil grade depends on where you live (climate). The choice of oil quality, in my opinion, is to always buy the premium grade.
If you live in a warm climate (seldom under 32 degrees), with an old car in good shape, I prefer to use SAE30W.
Don't mistakenly buy 10W30 or 5W30, those are much too thin for an old car - our oldies were not designed for the modern MPG saving oils. Also, don't buy the synthetic oils - they are also too thin, and very expensive!
As for brand names, I prefer either the NAPA premium brand, or Chevron RPM Delo 400 brand. These are both very highly rated oils, and yes, they do have high detergency. I'm sure the other major brand oils are just as good, I just don't have any experience with them. All good oils are marked with an SAE code as to quality - just buy the highest current rating, which is now SJ, I think (we may have some SK out there now, I might be a bit out of date.)
If you have to cope with temperatures below freezing before the next oil change, I'd use 20W50 oil, and if it gets really cold, like below zero when you will be starting the car, you'll have to use 15W40, but that should not be used in the hot weather.
Dick
