If you still don't understand why a 10W-40 oil is so much better for your engine than a mineral -based 20W-50 'classic' [old-fashioned] oil - the full answer is all over t'Internet. This link leads you to the BMW forum, and Dr Ali E Haas' articles.
The relationship between Power and Torque, and what these terms mean:
Everything you need to know about camshafts, profiles etc.
For All classic British cars, every wiring colour serves a particular purpose across all vehicles, so, with these codes, one look at any cable tells you exactly where it is going to - and from - and what it is ignition, battery or intermediate, fused or unfused, etc. No more guesswork.
The BS wiring colours I found on Marcel Chichak's site.
His site is fascinating and covers all manner of topics. To save you wading through the maze of his mental universe here are some direct links to areas of his site of interest on Lucas distributors:
This is several pages of detailed instruction and discussion.
A vast database of not only hundreds of 45D4 models but many more too!
Explaining the 18 variables affecting what is in 'your' correct distributor