Back in1967-1980 Austin Healeys were my everyday drivers. First a 65 BJ8, later a 67 BJ8. This is in the Denver CO metro area. Sometimes I would take the battery inside when the temps got below 0 degrees F.
Winter time temps here can get 24º below 0 F. I had a 22-mile one way to work, never missed work because my Healeys would not start. This was over a 10-12 year period. Used several tricks, 100 W light bulb under the hood, heated dip sticks etc. One time I used a Coleman two-burner stove under the pan for a while. Always made it home also. Never used 20W-50 oil, I had always used 10W-40 in my cars.
The Healeys with Mitchelin X tires were great in the snow and ice, It would go around cars that couldn't get up slick hills.
After 8-years of use and abuse, and some rust, restored the 67 BJ8. later in 1980 traded it in for a 1974 Mercedes 450 SL convertible. Got $8,000 trade in towards the $16,000 Mercedes.
Doug