I assume you've seen the Find A Grave listing for his grave?
https://www.findagrave.com/memorial/28679023/john-f.-oliverHere is a Fold3 memorial for John F. Oliver, serial number 11107136.
https://www.fold3.com/page/83436011-john-f-oliverThe above memorial shows 1932, which is obviously incorrect. I've seen this many times while researching others. Frequently, they get the last two digits inverted (i.e. 1932 instead of 1923). While searching the draft registration cards on Fold3, there are four "John Francis Oliver" from Massachusetts. None of which have birth years of 1923 or 1925 as you shared in a post. The four listed have the following info;
- 1910 - Born in Middleboro, MA - Residence on 16 Oct 1940, Middlesex, MA - Mary Frances Oliver (wife)
- 1922 - Born in South Boston, MA - Residence on 30 Jun 1942, South Boston, MA - Anna R. Oliver (no relationship listed)
- 1919 - Born in East Boston, MA - Residence on 16 Oct 1940, East Boston, MA - Mary C. Oliver (mother)
- 1914 - Born in Brockton, MA - Residence on 24 Oct 1942, Brockton, MA - Catherin Smith (grandmother)
Expanding the search outside of Massachusetts, I don't see any draft registration cards for "John Francis Oliver" with a birth year of 1925.
Newspapers.com is another resource I use. I'm not able to find any obituary or death notice for "John F. Oliver", "John Francis Oliver", or "Oliver, John F" in 1991.
I also took a look on Ancestry.com and built a tree using the information from the Find A Grave memorial. Interestingly, it shows a different middle name of Frederick, not Francis.