Gear oil, engine oil, brake pads.... most of them are over-specced for tootling about in our cars for a few thousand miles per year. I spent £50 on Lucas engine oil that was changed a year later after only 300 miles; great reviews, be all and end all of classic motor oil... but my use didn't justify it. If you're a fast driver, rallying or doing high mileage then it may justify additional cost for some of the more high-spec lubricants but for a low-use classic, good moderately priced product is perfectly adequate and performs no better or worse than the expensive stuff, especially if it's all serviced once a year at least.