GL 4+

API GL‑4+ is a transmission oil specification established by the American Petroleum Institute that defines the minimum requirements for protecting gear teeth, synchronizers and bearings in manual gearboxes, differentials and transaxles. Oils that meet GL‑4+ contain a balanced EP additive package with a moderate phosphorus content, providing sufficient resistance to extreme load while not damaging phosphorus‑copper synchronizers. They are intended for passenger cars, SUVs, light trucks and agricultural equipment where a standard manual gearbox or rear differential is used. Unlike GL‑5, GL‑4+ does not have high sulfide concentrations, thus preserving shift smoothness in synchronized gearboxes while remaining effective in medium‑heavy service conditions. The XENUM catalog features three GL‑4+ marked products, namely transmission oils X‑TRAN 75W90 GL4/5, X‑TRAN 75W80 GL4/5 and XT‑PRO 75W140, which meet these requirements and guarantee durability and reliability.