I think I can throw a little light onto the case of the overfilled sump. The motoring writer in question, who I believe is known as “Long John Kick Start” to his motor cycling friends, wrote, about two years or more ago, about the strange tale of the seizing up of BL 1800s.
Apparently a few drivers of the earlier 1800s were having serious problems with their engines seizing up on motorways and long journeys.
After much experimenting by British Leyland, including trying various new methods of the final boring of the cylinder bores, they finally came to the conclusion that the problem lay with incorrect calibration of the dipstick of all things! Thus with the oil level reaching normal, there was really a high level in the sump. Now when Mr. Average Motorist went on a long journey, before he set out he added a pint of oil, “just to be on the safe side”, the oil level now being excessively high, so much so that the crankshaft was churning the oil into a high quality froth, leading to a subsequent loss of oil pressure and the inevitable seizure.
G. S. C. Smith.
[There is only a pint in it, between “Full” and “Empty” in a Maxi.—ED.].