Hello Phil,
as nobody has leapt forward with the reply I shall offer you my thoughts on the matter of valve stem oil seals.
Probably not fitted on all P6 V8 engines and probably introduced during the (later) SD1 years.
Rimmer Brothers offer valve stem oil seals for inlet only for engines up to 1994 and neoprene type for inlet and exhaust from 1993 - not suitable for earlier engines as it requires the stepped valve guides.
I have bought a set of the earlier type to fit on to my early SD1 heads during overhaul prior to swapping for original heads and using composite head gaskets to go unleaded.
Hope this helps.
Regards, John.
