Originally Posted by
tartare
Can someone explain the oil issue in a little more detail?
Are tolerances so fine that the wrong grade will gum things up, or create excessive wear and tear?
Yes, I believe from fading memory that was the case, and a quick trawl through a few old bits n bobs stashed away and I found this, but how true or not I don't know.
The formulation of the oil was to withstand high temperatures and small tolerances between sleeve and cylinder wall and to prevent Oil breakdown between Sleeve and Cylinder wall increasing friction thus causing increased wear and tear, due to high temps.
The oil appears to be called 100U oil, although an old post elsewhere on the subject by Pete Rushen from TFC from his says in the RAF on the Beverley also states RAF used OM270 oil when not in the tropics.
It also appears that the last batch of 100U oil was destroyed back in 2005 when Buncefield depot exploded.