Castrol Cyltech 70f Cylinder Oil

Specifications

OEMCastrol Marine (bp)
Product typeTwo-stroke crosshead engine cylinder oil
Base Number (BN)70 mg KOH/g
SAE viscosity gradeSAE 50
Kinematic viscosity @ 100Capprox. 19.5 mm2/s (cSt); legacy Cyltech 70 PDS value, 70f range stated ~19-21 cSt
Intended fuel / applicationSlow-speed two-stroke crosshead engines burning mid-range/residual fuels; legacy Cyltech 70 rated for ~1.0-3.5% sulphur fuel
Engine-OEM approvalsMAN Energy Solutions (MAN ES), WinGD, JEC
AvailabilityNew reformulated 'f' range available from March 2025 (initially 70f and 100f)

Technical notes

Cyltech 70f is the 2025-reformulated successor to Castrol Cyltech 70, a BN 70, SAE 50 cylinder oil for slow-speed two-stroke crosshead engines. The mid-BN alkalinity suits engines burning mid-range residual fuels (the legacy Cyltech 70 PDS specifies roughly 1.0-3.5% sulphur fuel). The reformulation targets the higher cylinder temperatures and pressures of modern slow-speed engines, with improved thermal and oxidative stability and deposit control on pistons, rings and liners. Following over 75,000 hours of field testing it carries approvals from MAN ES, WinGD and JEC. Grade and feed-rate selection are fuel-sulphur and engine-load dependent and must be confirmed with the engine OEM and Castrol before use.

Compliance

Castrol Cyltech 70f is approved by MAN Energy Solutions, WinGD and JEC for slow-speed two-stroke crosshead engines, but final grade and feed-rate selection must be confirmed against the engine maker's lubricant recommendations.

Compatibility

Other parts in this series

Related

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Frequently asked questions

What is the Base Number and SAE grade of Castrol Cyltech 70f?
Cyltech 70f is a BN 70 (mg KOH/g), SAE 50 cylinder oil, carrying the same BN/viscosity designation as the Cyltech 70 it replaces (confirmed on the official Castrol Cyltech 70 product data sheet).
Which engines and fuels is Cyltech 70f suited to?
It is formulated for slow-speed two-stroke crosshead engines burning mid-range residual fuels; the legacy Cyltech 70 PDS rates this BN level for roughly 1.0-3.5% sulphur fuel. Selection must be confirmed with the engine OEM and Castrol.
Is Cyltech 70f OEM approved?
Yes. Castrol states Cyltech 70f is approved by MAN Energy Solutions (MAN ES), WinGD and JEC following extensive field testing.
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