Engine, 3.6L V6, SIDI, DOHC, VVT, automatic stop/start, 335 hp at 6800 rpm, 284 lb-ft at 5300 rpm

Years 2016–20, 2025–26 Models 4 Factory citations 15

Also described as Engine, 3.6L V6, SIDI, DOHC, VVT, Active Fuel Management, automatic stop/startEngine, 3.6L V6, direct injection, variable valve timing

Also documented for Buick Chevrolet GMC

Documented applications

ATS — Alpha (2013–2019)

2018 Factory-verified

335 hp

GM factory document — 2018 cadillac ats coupe fleet order guide wayback, p.4.
GM factory document — 2018 cadillac ats sedan fleet order guide wayback, p.4.

CT6 — Omega (2016–2020)

2017–2019 Factory-verified

2017: CT6 3.6L AWD, Luxury 3.6L AWD, Premium Luxury, Platinum: S; 2018 and 2019 from the 2018 and 2019 order guides, both 3.6L AWD trims S (GM documents)

GM factory document — 2017 cadillac ct6 fleet order guide wayback, p.4.
GM factory document — 2018 cadillac ct6 order guide copy gm authority, p.58.
GM factory document — 2019 cadillac ct6 order guide copy gm authority, p.52.
2016, 2020 Single-source

2016 and 2020 rest only on GM Authority's LGX engine page (https://gmauthority.com/blog/gm/gm-engines/lgx/); the article does not credit GM for its codes, and no factory list in the archive covers those years

XT5 — C1XX (2017–2026)

2025–2026 Factory-verified

Sport: S; Premium Luxury: O; Luxury: not available; GM Authority engine page lists this code

GM factory document — 2025 cadillac xt5 fleet order guide rpo codes, p.1.
GM factory document — 2026 cadillac xt5 fleet order guide rpo codes, p.1.
GM factory document — 2025 cadillac xt5 fleet order guide, p.8.
GM factory document — 2025 cadillac xt5 fleet order guide, p.17.
GM factory document — 2025 cadillac xt5 fleet order guide, p.35.
GM factory document — 2026 cadillac xt5 fleet order guide, p.10.
GM factory document — 2026 cadillac xt5 fleet order guide, p.17.
GM factory document — 2026 cadillac xt5 fleet order guide, p.36.

XT6 — C1XX (2020–2025)

2025 Factory-verified

Premium Luxury: S; Sport: S

GM factory document — 2025 cadillac xt6 fleet order guide, p.8.
GM factory document — 2025 cadillac xt6 fleet order guide, p.63.

This page aggregates every documented appearance of LGX in the Cadillac reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.