Personally I believe in starting the engine and, as long as stuff like oil light, alternator light, little cold engine "tappy noises" (like the Fire engine's cam follower rattle), all settle down then drive straight off, but gently without either labouring or applying excess revs to the engine. Just drive it lightly loaded. I do this until I judge the engine oil is up to at least 3/4 of full operating temp. My newish Ibiza can display it's oil temp on the little panel between the speedo and rev counter and I've observed that reasonable oil temperature is achieved in roughly twice the time it takes the coolant to reach full operating temperature. This engine is turboed so I'd expect it to heat it's oil more quickly than a normally aspirated engine so it's probably the case that many engines won't achieve full operating temperature of the oil for about three times as long as it takes the coolant to register "normal". It's good to keep this in mind before mashing the throttle to the floor?
I don't believe in oil additives at all, preferring to spend my money on a really good oil in the first place, especially where transmission oils are concerned. Fuel additives, especially for injector and system cleaning, I do believe have a roll to play. I'm running this stuff:
https://www.powerenhancer.co.uk/archoil-ar6900-p-max-advanced-petrol-synthesis.html in the Ibiza just now in the hope it may slow the build up of carbon deposits in it's direct injection inlet tract. Probably won't make much difference, but I can hope - suspect I'll be doing a bit of walnut blasting if I keep her long enough?
Although early on in my career I saw a lot of BL diesels - With their old CAV In line and DPA type pumps (still got my swan neck for spill timing!) the only newer diesels I've looked at have been the old pre PD and then the PD VAG engines. Looked at the 1.6 CR in my boy's last car (Fabia Scout) but rapidly withdrew and punted it to the specialist quick time! The older engines used to clog up their EGR, inlet manifold and inlet ports but good! Take a look on you tube for some entertaining videos of people with innovative ways to clear the deposits! I couldn't believe my old VE 1.9 tdi could still run with how much the inlet manifold bores were closed down to!
Regarding tools, I too have many of my old Britools still as well as some King Dick and German Hazet open enders which seem to resist spreading jaws much better than more modern stuff. I also still have my first serious tool purchase, a 1960's German made Kampfman socket set with Whit and AF sockets, bought while i was still in college and, just occasionally, they still get me out of trouble when hammered onto modern worn/corroded fixings. Never owned, or lusted after, anything with Snap On stamped on it. Also agree that for "serious" home use stuff from the Halfords advance/professional range, Draper, Laser, Neilsen and many other "middle of the road" brand names are really very acceptable and a good alternative at a reasonable price if you're not earning your daily bread with them.