Old Overloaded Transformer
MIDWEST was challenged by a technical skeptic to give him just one example of a large old oil filled transformer that obviously outlasted its useful life expectancy. Apparently he got into a heated argument with some old timer electricians who claimed they trusted the old transformers a lot more than new stuff they had seen. It may not be wise to argue with experienced electricians. They have ways to argue with enthusiasm and sometimes expressions that leave little doubt as to the strength of their convictions. And they have real world experience, usually a good trump card.
MIDWEST gave him the example of two 2000 Kva old substation transformers built in the 1950s that have been running at 107% full load for the last 20 years. These are not rebuilt or reconditioned transformers. But they are pretty inefficient and about 3 times as large as a new oil transformer the same kva. MIDWST is not suggesting old transformers are better than new. But, be careful when buying new transformers. Specify quality and reliability, or you may get cheap and disposable.