Robert/Richard, Happened to be re-reading D.Culshaw's book,"Alvis 3litre in detail", p72,states that the first 25 TD21s used engines left over from unbuilt TC108Gs , to me, this implies no external oil filter until chassis 25971, assuming crankcase part no. C6691 was used. Season's Greetings to all Peter Posted by Peter Martin 06/12/2016 11:10:41