The boys at practical classics speak very highly of:
https://www.lubricantsuppliers.com/p...1-bulldog-bdx/
Sadly, many of those working as mechanics are none of those things.
I do a desk job and love working on cars, both our daily drivers and classics, as a complete change in the evenings and at weekends.
The coil pack failed recently on our Zafira B. Halfords were (amazingly) the cheapest supplier and the job was done in about 20 minutes. I got a satisfaction hit and probably saved £100 or so quid.
I recently changed the thermostat on our Panda, a fiddly job that took a couple of hours but again I probably saved a couple of hundred and am still enjoying the fact that it gets properly up to temperature again.