SYNTHETIC TRANSMISSION OIL SIGNIFICANTLY EXTENDS DRAIN INTERVALS
For city buses a drain interval of 6000 hours should be possible with synthetic oil, Allison says. For operators looking to improve transmission reliability whilst extending drain intervals switching from mineral to synthetic oil would be the way. British operator Plymouth City Bus, with a fleet of over 170 buses, took this step, increasing drain intervals by over three times.
Transmission fluid is a critical element in the performance and longevity of every automatic transmission. Responsible for transmitting power and torque between the engine and final drive, it protects, lubricates and cools key components. Conventional transmission fluids are petroleum-based, can oxidize quickly and in turn undermining the effectiveness of the additives, viscosity enhancers and detergents. Over time, this causes a sharp reduction in viscosity and degrades the ability to provide adequate lubrication. Moreover, sludge and varnish deposits erode shift quality and increase component wear, leading to costly downtime and maintenance.
With Castrol, Allison developed TranSynd oil as a synthetic oil for automatic transmissions, but states that any TES295 fluid, approved by Allison, can deliver maintenance, environmental and operating benefits experienced by Plymouth City Bus. Two thirds of the fleet are equipped with Allison’s fully automatic transmission and are now running on synthetic oil. Historically, they changed oil every 40,000km; that is approximately every 12 months. Since the switch to TranSynd and the use of oil testing she now changes the oil every 120,000km (6000 hours), which equates to every three years. TranSynd also offers the operator additional environmental benefits; with oil lasting longer there is a marked reduction in the amount of oil being disposed.
Allison Transmission recommends that customers use fluid analysis as the primary method for determining fluid change intervals. Analysis will look at oxidation, contaminant levels and viscosity. Glycol and water are probably the most common and harmful contaminants found in a transmission. Water is a poor lubricant and can cause corrosion. Glycol can attack the bonding material used to join the clutch friction material to the steel plates.
The recent addition of Allison’s new advanced prognostics capability to its entire range of automatic transmissions provides operators with a electronic fluid and filter change indicator. This feature monitors the specific operating conditions for each bus which allows both fluid and filter changes to be optimized when using a TES295 certified fluid.
