Originally Posted by
Buster15
That was the biggest risk at that time.
The early Mk101 engines had a pretty inefficient Breather system that allowed a fair amount of oil to be discharged overboard from the external gearbox.
This resulted in relatively high oil consumption (HOC).
The spec was 0,5l/hr which most engines achieved but the trend increased with age.
High speed low level also increased oil consumption.
The usable oil was about 8.5l and hence engines using more than the limit could have been oil limited.
This was resolved by improving the engine internal oil system and gearbox breather system as well as increasing the usable oil content.
Even the Mk103 had issues with oil consumption and all the GW1 engines had their breather carbon seals replaced. ISTR the Mk103's had better cooling for the module 11 bearing overheat issues and of course the all attitude oil tank rather than the clunky SLS feature of the Mk101.