Engine, 4.1L V6, 252 cu in, 4 barrel

VIN code 4; Wikipedia's Buick V6 article gives the LC4 to the fifth-generation Electra through 1984, and its Electra article names the Buick 252 V6 among the generation's engines; gnttype.org's 1984 Buick VIN table prints it in the Electra Limited and Park Avenue block, a second source for 1984; its 1983 Electra block is word for word the 1984 one, so 1983 rests on Wikipedia alone and the row stays single-source

optional (VIN code 4); Wikipedia's LeSabre article names the 252 V6 as a 1983 option, dropped for 1984, and its Buick V6 article prints LC4 for the LeSabre; gnttype.org's 1983 Buick VIN table prints it for the LeSabre but repeats its 1984 table word for word, so it is not counted as a second source; 1984 and 1985 are left out: gnttype.org's 1984 and 1985 tables and the Buick V6 article's application line also give it, but the LeSabre article says it was dropped for 1984, and the 1985 NICB manual's Buick engine table prints VIN code 4 in its 1984 column but not in its 1985 column

gnttype.org's 1983 and 1984 VIN engine tables; Wikipedia gives the 4.1L to the Regal through 1984

the 252 V6 (VIN code 4); Wikipedia's Buick V6 engine article prints LC4 and lists the Riviera for 1981–1984 and its Riviera article names the 252 as the standard engine from 1981; gnttype.org's 1984 Buick VIN table prints LC4 for the Riviera Luxury, a second source (owner ruling, 2026-11-05: a T3 page that names the code for the nameplate, with Wikipedia dating every year), its 1983 table repeating the 1984 one, so 1983 rests on Wikipedia's dating; 1985 is left out because the 1985 NICB Buick engine table prints VIN code 4 in its 1984 column but not in its 1985 column and Wikipedia's article gives the engine through 1984