There are only two kinds of documents in current usage that spell out the year -- legal documents, and wedding invitations.
Legal documents normally spell the year in lowercase, such as in this numbing bit of prose from West Virginia:
For any tax imposed under the provisions of this article with respect
to any taxable year prior to the first day of January, one thousand
nine hundred eighty-three, a resident individual shall be allowed a
West Virginia exemption of six hundred dollars for each exemption for
which he is entitled to a deduction for the taxable year for federal
income tax purposes.
Some legal documents capitalize everything for extra pomp, but it's uncommon:
In testimony whereof, I hereunto subscribe my hand and affix the seal
of said Court, at Office, in Nashville, the 6th day of December in the
Year One Thousand Nine Hundred Eighty-Four and in the 209th Year of
American Independence.
Wedding invitations, as noted, tend to capitalize the first letter only; however, this seems to be the only justification I can find:
The “T” in Two thousand doesn’t have to be capitalized but everyone
does it so it would probably look incorrect if it wasn’t and it will
look more polished if it is capitalized.
So, in modern usage, it appears that the rules for capitalization are:
- Spell the year out in lowercase.
- Except in wedding invitations, where the first letter is capitalized because everyone does it.
All of your examples should be spelled out in lowercase because they do not describe unique, one-of-a-kind elements, rather they describe a type or class of element. One way to verify is to ask if you can use an article in front of them, such a "a" or "the" or if you can make them plural; if so, then they are not proper nouns and should not be capitalized. For example, you could say the electronic stability control on my Ford works much better than the electronic stability control on my Toyota.
Best Answer
When used as an adjective meaning ‘of or pertaining to any or all of the nations other than the Jewish’, the OED states that ‘it is now usually written with capital initial’. Similarly, it says of the noun meaning ‘one of any nation other than the Jewish’, it is ‘usually with capital G’.