Buick Skylark — N-body (sixth generation) (1986–1991)

The sixth-generation Skylark was Buick's front-drive N-body compact for the 1986–1991 model years, a four-door sedan from 1986 and a two-door coupe, sold under the Somerset name before the 1988 model year (Wikipedia). The NICB VIN manuals list the Skylark Custom and Limited four-door, the Custom two-door and the Grand Sport two-door in their 1987–1991 columns. No GM order guide, data book, Heritage kit or service RPO list for this Skylark is in the archive, and no Chevrolet kit shares its platform, so only engine codes are listed: Wikipedia's Skylark article and its engine articles name and date the engines, and gnttype.org's 1986 and 1987 Buick VIN tables print the 2.5 L engine's RPO code for the Skylark. No source read ties a transmission, axle, option, package, paint or trim code to the Skylark with a year, so none is listed.

Codes

Engines

Code	Description	Years	Models/Notes	Confidence
L68	2.5 L L4, throttle-body fuel injection (VIN U)	1986–1991	Wikipedia's Skylark article dates it 1986–1991, supplied by Pontiac; gnttype.org's 1987 Buick VIN table prints it for the Skylark Custom and Limited four-door, a second source (owner ruling, 2026-11-05: a T3 page that names the code for the nameplate, with Wikipedia dating every year); the 1986 NICB manual's engine table prints the 2.5 L four-cylinder throttle-body letter U	confirmed
LN7	3.0 L (181 cu in) V6, multiport fuel injection (VIN L)	1986–1988	Wikipedia's Skylark article gives it to the Skylark for 1986–1988 and says it was replaced by the 3.3 L V6 (1989); it was the engine of the T-Type, new for 1987; gnttype.org's 1986 and 1987 tables print LN7 only on the Somerset rows, never the Skylark's, so the nameplate's own sources print the code only in Wikipedia; Wikipedia's Buick V6 article lists the Skylark 1986–1988 (not an independent source); the VIN letter is from the 1986 NICB engine table (3.0 L V6 MFI)	single-source
LD2	2.3 L L4, DOHC, fuel injection (Quad 4)	1988–1991	Oldsmobile-built; Wikipedia's Skylark article and its Quad 4 engine article both give it to the Skylark 1988–1991 (not independent); no other source read prints the code for the Skylark	single-source
LG7	3.3 L V6, fuel injection	1989–1991	160 hp, replaced the 3.0 L V6; Wikipedia's Skylark article gives it 1989–1991; its Buick V6 engine article lists the Skylark for 1989 on (not independent); no other source read prints the code for the Skylark	single-source

Sources

Factory documents (T1)

No Buick factory document or Heritage kit for the 1986–1991 Skylark is in docs/factory-docs/ or docs/heritage-ocr/, and the brief lists no Chevrolet kit pages, so none is cited.

Other sources

https://en.wikipedia.org/wiki/Buick_Skylark — sixth-generation infobox, text, production table and engine list (retrieved 2026-11-05 as wikitext, action=raw)
https://en.wikipedia.org/wiki/Quad_4_engine — LD2 applications (retrieved 2026-11-05 as wikitext)
https://en.wikipedia.org/wiki/Buick_V6_engine — LN7 and LG7 applications (retrieved 2026-11-05 as wikitext)
https://en.wikipedia.org/wiki/Iron_Duke_engine — Tech IV 2.5 L applications (retrieved 2026-11-05 as wikitext)
http://www.gnttype.org/general/vin.html — per-year Buick VIN tables with the Skylark's 2.5 L RPO code (retrieved 2026-11-05); the tier verification covered only the site's Regal RPO list, the owner ruled on 2026-11-05 that this page counts as a T3 second source for the codes it prints. Its 1986 table repeats the 1987 table's engine and plant blocks, so only the 1987 table is cited.
NICB Passenger Vehicle Identification Manual, GM sections (T4): docs/reference/nicb/nicb1986-gm.txt pp.37–38 and nicb1991-gm.txt p.35, read on the page images — Skylark car-line names and the 1986 engine VIN letters