Eastman BP 274 Aircraft Turbine Engine Lubricating Oil
BP Turbo Oil (BPTO) 274 is a synthetic oil having a
viscosity of 7.5 centistokes at 210°F and meets DEF
STAN 91-98/1 (replaces British Military Specification DERD 2487). It is formulated with special synthetic base stocks into which are incorporated additives to inhibit wear, oxidation, and foaming. It provides good
high temperature performance and load-carrying ability.
These features provide long trouble-free performance
under severe conditions. Although this is not always
appreciated, synthetic oils of this type are not all
identical. The performance advantages of BPTO 274 are
achieved only by careful selection and balance of base
stocks and additives to provide the desired performance.
BPTO 274 is approved for certain Rolls-Royce engines and associated accessories. The approvals listed below
are current as of the time of printing; however, the respective manufacturer’s manuals and service bulletins
should be consulted.
Dart: BPTO 274 is approved for use in all marks of the Dart engine (R-R Service Bulletin DA 70-4).
Gnome: BPTO 274 is approved for use in all marks of the Gnome engine (engine type certificate data sheet
for each respective mark).
Orpheus: BPTO 274 is approved for use in all marks of the Orpheus engine (Bristol Siddeley letter dated January 18, 1965).
Pegasus: BPTO 274 is approved for use in all marks of the Pegasus engine (Bristol Siddeley letter dated January 18, 1965).
Proteus: BPTO 274 is approved for use in all marks of the Proteus engine (Bristol Siddeley letter dated April 14, 1967).
Tyne: BPTO 274 is approved for use in all marks of the Tyne engine (R-R letter dated October 13, 1964).
Viper: BPTO 274 is approved for use in Marks 8, 9, 11 and 22-1 (MK 22-1 is license built by Piaggio) of the
Viper engine (Bristol Siddeley letter dated January 18,1965).
Accessory Drive Gear Boxes: BPTO 274 is approved for use in all accessory drive gearboxes and
associated components used in R-R Dart engines (Dowty Rotol Service Bulletin No. 83-58). BPTO 274
is also approved for use in Dowty Rotol accessory drive gearboxes in R-R Tyne applications.
Propeller Systems: BPTO 274 is approved for use in propeller systems associated with R-R Dart
(Dowty Rotol letter dated March 25, 1965).
Hawker Siddeley Dynamics: BPTO 274 is approved for the propeller system incorporated with Tyne engines on Canadair CL-44 aircraft.
Solar: BPTO 274 is approved for use in auxiliary power unit T-62T-25 (Solar Service Document 1966C).
Pratt & Whitney Canada: BPTO 274 is approved for use in accessory gearboxes incorporated with Tyne
engines on Canadair CL-44 aircraft (Pratt & Whitney Canada letter dated January 12, 1967).
FeaturesLoad Carrying: BPTO 274 provides load carrying ability, as measured in the IAE Gear Machine and Ryder Gear Tests, well in excess of requirements established
by the engine and equipment manufacturers. Long life
of bearings, gears, and other highly loaded lubricated
surfaces is thus assured under normal operating
Cleanliness: Minimum formation of carbon, varnish or sludge deposits is one of the characteristic
advantages of BPTO 274 under temperature conditions
normally encountered in turboprop engines.
Bulk Stability (resistance to physical or chemical change resulting from oxidation): The high degree of oxidation resistance of BPTO 274 permits long periods of severe operation without significant increase in viscosity or total acidity, the two principal indicators of product oxidation. The need to change oil because of oxidation effects is rare when using BPTO 274. Most users find it unnecessary to make oil changes in spite of occasional mechanical abnormalities that create
unusually severe oxidizing conditions.
COMPATIBILITY: While considerable laboratory data is available to demonstrate the compatibility of BPTO
274 with metals, elastomers and other lubricants, the
extensive airline experience most adequately
demonstrates this property. BPTO 274 is compatible
with other turbo oils meeting the same specifications to
the extent that an inadvertent mixing or emergency topoff
with another approved brand will not cause additive
separation to occur. However, most engine builders
do not recommend indiscriminate mixing of approved oils and we agree with this principle.
Shelf Life: The shelf life of BPTO 274 can extend beyond ten years when stored in original, unopened
quart cans under acceptable conditions, such as away
from extreme heat and moisture. Likewise, drummed
product has an expected shelf life of three years minimum. For all package styles, shelf life can be increased
significantly beyond those stated above, depending
upon storage conditions.
SpecificationsDEF STAN 91-98 (DERD 2487)
NATO Code: 0-149