Buick Somerset — N-body (1985–1987)
The Somerset (sold as the Somerset Regal in 1985) was Buick's front-drive N-body two-door compact for the 1985–1987 model years (Wikipedia). The NICB VIN manuals list the Somerset Regal and Somerset Regal Limited in 1985 as a two-door notchback coupe, the 1987 manual lists the Somerset Regal and Custom and the Somerset Regal Limited for 1985–1987 and a Somerset T-Type for 1986 only. No GM order guide, data book, Heritage kit or service RPO list for the Somerset is in the archive, and the archive holds no Chevrolet kit for this platform, so only the two engine codes are listed: Wikipedia and the per-year Buick VIN tables on gnttype.org name and date LN7, and Wikipedia alone names and dates L68. No source read ties a transmission, option, package, paint or trim code to the Somerset with a year, so none is listed.
Codes
Engines
| Code | Description | Years | Models/Notes | Confidence |
|---|---|---|---|---|
| LN7 | Engine, 3.0L V6, 181 cu in, multiport fuel injection (VIN L) | 1985–1987 | the Buick V6 introduced for the Somerset, 125 hp, with the three speed automatic only (Wikipedia's Skylark article); Wikipedia's Buick V6 engine article prints LN7 and VIN code L and lists the Somerset for 1985–1987; gnttype.org's 1986 and 1987 Buick VIN tables print it for the Somerset Custom and Limited, a second source (owner ruling, 2026-11-05: a T3 page that names the code for the nameplate, with Wikipedia dating every year); its 1985 table repeats the 1986 table, so 1985 rests on Wikipedia; the NICB manuals print VIN L for the 3.0L V6 MFI but no RPO codes | confirmed |
| L68 | Engine, 2.5L L4, 151 cu in, throttle-body fuel injection (VIN U) | 1986–1987 | the Pontiac-built Iron Duke four; Wikipedia's Skylark article lists L68 for the N-body generation from 1986 and its Iron Duke article lists the Somerset for 1985–1987; gnttype.org's 1986 and 1987 Buick VIN tables print L68 only on the Skylark Custom and Limited rows, never on a Somerset row, so they are not a second source for this car; 1985 is left out because the Skylark article's engine list starts the code in 1986 and gnttype's 1985 table repeats its 1986 table; the NICB manuals print VIN U for the 2.5L L4 TBI but no RPO codes | single-source |
Sources
Factory documents (T1)
No Buick factory document for the 1985–1987 Somerset is in docs/factory-docs/ or docs/heritage-ocr/, and no Chevrolet twin-kit page was listed for this doc, so no row carries an [FD] or [HK] citation.
Other sources
- https://en.wikipedia.org/wiki/Buick_Somerset — redirects to the sixth-generation section of the Buick Skylark article; infobox, prose, production table and engine list (retrieved 2026-11-05 as wikitext, action=raw, from the Buick Skylark page)
- https://en.wikipedia.org/wiki/Buick_V6_engine — LN7 introduction, VIN code L and applications (retrieved 2026-11-05 as wikitext)
- https://en.wikipedia.org/wiki/Iron_Duke_engine — Somerset application years (retrieved 2026-11-05 as wikitext)
- http://www.gnttype.org/general/vin.html — per-year Buick VIN tables with the Skylark and Somerset engine RPO codes (retrieved 2026-11-05); the owner ruled on 2026-11-05 that this page counts as a T3 second source for the codes it prints. Its 1985 table repeats the 1986 table (Skylark sedan rows and all), so the 1986 and 1987 tables are the ones cited.
- https://rparts-sites.s3.amazonaws.com/dec399b0838336997484042ed2af1004/design/rpoCodes.pdf — GM-wide code list (T3), used to check code meanings only (retrieved 2026-11-05)
- https://jameshalderman.com/wp-content/uploads/2019/04/RPO_Codes.pdf — GM-wide code list (T3), used to check code meanings only (retrieved 2026-11-05)
- https://decoderpo.com/?s=somerset — T3; the search returned only the site's generic lookup page, no Somerset-specific page (retrieved 2026-11-05)
- NICB Passenger Vehicle Identification Manual, GM sections (T4):
docs/reference/nicb/nicb1985-gm.txtp.28 andnicb1987-gm.txtpp.38–39, read on the page images — Somerset series names, VIN series symbols and engine VIN letters