LUBRICATION GUIDE
DIN 51524 HLP Meaning: Hydraulic Oil Classes Explained
By the PCG Technical Desk · Updated 27 September 2026
Quick answer: DIN 51524 is the German standard for mineral hydraulic oils. Part 1 = HL (rust and oxidation inhibited), Part 2 = HLP (HL plus anti-wear additives) and Part 3 = HVLP (HLP with a high viscosity index). When a manual says “HLP 46”, it means an ISO VG 46 oil meeting DIN 51524 Part 2.
What the letters mean
H = hydraulic oil, L = with rust and oxidation inhibitors, P = with anti-wear (pressure) additives, V = high viscosity index.
What DIN 51524-2 tests (overview)
The standard sets requirements for viscosity, oxidation stability, rust and corrosion protection, demulsibility, air release, foaming, seal compatibility and anti-wear performance, including gear and pump wear tests.
SERVO oils against DIN 51524
- Part 2 (HLP): Servosystem HLP (also HLP AF and HLP N), per IOCL.
- Part 3 (HVLP): Servosystem HVLP 22/46/68, per IOCL.
- H / HL: Servocirol, per IOCL.
Note: IOCL lists the standard Servosystem 68 against IS:10522 and the Vickers V-104C test, not DIN 51524-2. If DIN 51524-2 is mandatory, order HLP.
Outside Karnataka? The technical information on this page applies anywhere in India. PCG Business Solutions supplies SERVO in seven Karnataka districts. If you are in another state, send us your requirement and we will point you to IndianOil's authorised channel for your area, or answer any technical question about the grade.
