This is evident with the Jan '46 MoS correspondence regarding the Austin cars, where the Austin technical people state that for use with HD30, the pistons would require additional scraper rings
It required a scraper ring full stop
; according to Austin's reply to the MoS, prior to this there wasn't any on their four-cylinder car engine pistons at all.
the urgency might have meant just a few cursory rig tests were conducted using whatever lubricant was available. There were certainly no extensive tests using HD30, otherwise the problem would most likely have come to light.
We don't know
that there were no or cursory tests yet, that's what we still need to establish. If there were tests, I doubt that they'd be done with anything other than HD30 - think the D.M.E. would let them away with that?
Once againe we're starting
from the position of knowing what was done (they hoped!) to eradicate a problem; we don't know the cause of the problem, the definition of the problem apart from "overheating", or the (various?) steps along the way to identifying that an increased-clearance piston skirt would supposedly eradicate it.
Then they are asked to provide a wading spec. using higher octane MT80,....
What we DON'T know is if those two requirements came together
...and either test problems or general concerns about heat expansion of the piston lead them to reduce the clearance of the piston skirt.
However - we DO know more about this
aspect. These trucks were specifically "recalled
" to have the new pistons fitted; they had already been issued
and in use and waterproofed
....the waterproofing having to to be done again by REME after the pistons were fitted.
So that would read as if something more...impactful....than testing problems or general concerns had occured? And the clock was DEFINTELY counting!
At this point I can understand
if testing of the new increased-clearance piston turns out to have been less than thorough!
Problems then emerge in service, and there must have been some comparative tests using HD30 and other lubricating oils (M220 or whatever the "civil" spec. was), and it is revealed HD30 does indeed create problems for the new piston design. They therefore specify a new set of rings that are specifically for use with HD30 only, and are marked as such.
I wouldn't assume...given the military mind, it was the D.M.E. War Office driving the problem by then
...that the "HD30" mark on the rings meant anything more than it had been "tested for compatibility with HD30
" - that being the oil specified
for use in the K5! I doubt that the urgent resolution of the problem gave them time
for anything other than testing in the specific application of K5 fitment at that point...
Also remember that any benchtesting before fitting in the three trial vehicles the D.M.E. mentions wouldn't have been done by Austins anyway - it would have been done by Wellworthys!
The rings were THEIR proprietary product
One other consideration - I don't know HOW Austins marked the outside of their spares' packaging...especially products supplied by a third party and re-packaged
by Austins...but the "HD30"-marked pistons would have been destined for K6s too
For information - things had got rather complicated on the lube front by then
Every time a new application appeared or a new grade or specification was needed that existing ones didn't cover - a new oil grade was brewed
By the winter of 1944-45 there were 361 different grades of oil and grease
in use in the armed forces of the United States, Canada and Great Britain!
Over the winter, after problems were experienced with there being too many varying grades...the Staff History notes that when the temperatures plummeted, REME dutifully changed lubes to suit the ambient temperatures - but sudden spikes in temerature THEN rendered these less than effective!...there were also fears that frequent changes attempting to react to all the changes would result in mixing compounded and hypoid oils if crankcases, gearboxes etc. weren't fully drained during each change - a Joint Associated Services Lubricant Panel was set up and they managed to get the number of lubricants in use down from 361 to...118
For example - 68 different types of grease were withdrawn from service...
Twenty years ago we had Johnny Cash, Bob Hope and Steve Jobs. Now we have no Cash, no Hope and no Jobs....
Lord, please keep Kevin Bacon alive...