Components that had been chosen for cheapness rather than longevity were replaced and the total oil loss system replaced with a conventional one. Unfortunately the Vipers design had not allowed for any maintenance and reoccurring maintenance issues were common on early variants.
The Rolls-Royce Griffon engines used it the Avro Shackleton utilised water methanol injection to boost power on takeoff and this adversely affected the engines reliability. In 1965, in an attempt to resolve this issue, the Avro Shackleton MR Mk.3 Phase 3 maritime patrol aircraft had their water methanol injection system replaced with two Viper Mark 203 turbojets in the outer engine nacelles, they were modified to run on high octane petrol (AVGAS) reducing their service interval to 200 hours, but were only needed at full power for two minutes during takeoff (see bottom picture). It is rumoured that a Shackleton flew on only these engines in 1995, although this is unsubstantiated, as each of the vipers produced similar thrust as a Rolls-Royce Griffon, and the Shackleton could fly with only two engines, it would seem to be possible.
Due to company mergers and acquisitions the Viper has been marketed as the Armstrong Siddeley Viper, Bristol Siddeley Viper and finally the Rolls-Royce Viper.