Rolls Royce Viper engines
I flew a lot of time in an HS 125 403B and it had these engines. The F/O's seemed to lose the toss, more than the Captain, so they ended up more on the pylons, checking the oil and topping it up if necessary.
The Viper at that time had the reputation of , if you could light it off it would then never let you down.
Tmb