When I was a young instrumentation engineer in 1975 the old works manager told me that the only instruments that he trusted where a dip stick and a mercury in glass thermometer. They certainly have fewer and better understood failure modes than most instruments.
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR
A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke