I think you may be over egging the pudding ,lubrication technology has moved on in leaps and bounds since these engines were designed . The only real concern re what you use in them is that its not too thin , so it leaks out everywhere. A half decent mineral or semi syn multigrade will give better protection than the original spec oils were ever capable of . I used 20/50 in the various rover engines , some that worked hard and never had any probs over extended mileage . I do believe in using the best where it will justify , My 110 runs Redline in all the transmission components, for a number of years due to the harsh environment it has been in . My 90 on the otherhand just uses run of the mill lubricants , as its usage doesnt justify more . JMHO