Patman, you are right. It does not get that cold in Galveston. But I lived in NY City for a long time too, 1990-1993 I had a small-engine import subcompact that had only GTX 20W-50 in it, I would not allow the mechanics to put in any other motor oil. Ah, that car and the oil in its crankcase. Even when I had to spend 30 minutes to dig it out of its snow and ice tomb, it started without a hitch, first try, every time. I always had oil pressure from the first second.
1994-1998 I had a 351 cu. inch V-8 Bronco[year 1981 model? somewhere around 1981. Can't recall.]. This in New York, too. For this one, I decided to go with Castrol HD-30 monograde dinosaur oil. Some Summers I would use the heavier HD-40. Again, no problems in hot weather or cold. Almost-Instant oil pressure, about 3 sec after turning the key.
Concurrent with the Bronco, I also used and had the responsibility of maintaining my girlfriend's 1986 Thunderbird with 2.8L V-6. This one had, again, exclusively Castrol oil in it.....10W-40, my NY mechanic recommended and I agreed with him. In the coldest NY winters, that T-Bird started first try, every time[Ah, except for electrical problem episodes...Ford owners will give a knowing smile]. T-bird was sold in 10/2000 or 11/2000.
Both Bronco and T-Bird had in excess of 150,000 miles on them. Till the day they were sold, neither myself nor my mechanics knew what they looked like on the inside.
The small import I had from '90-'93, it was stolen after I had only owned it 2.5 or 2.75 years. By the time it was stolen, it had 58,000 miles on it. I learned one thing when I had it(apart from never parking a non-Ford on the street in NY City, hahaha!!!!!!). It's that not all 20W-50 oils are created equal. Once, a New Jersey mechanic snuck in a load of CITGO 20W-50 when I wasn't looking. The next day, I found that my car would not rev. It was like, glue in my engine. I drove back to the shop and said, what gives? The guy admitted sneaking CITGO oil into my engine. I made him dump the whole load and filter too, and replace with GTX 20W-50. Ran like new again after the GTX was put in.
With the small import, I went to Buffalo, Syracuse, Oswego a lot. Whooo-Wee, talk about cold!!!!! Never mind cold morning starts being hard on my engine. I thought I would die of frostbite and hypothermia before my engine felt any ill-effects of cold starts! Even in those Western NY State conditions, I never had a problem with mineral oil.....Castrol mineral oil. So, believe me.....synthetics.....ya don't need 'em.