I had the habit of starting my Stag engine every monht and running it to warm up. A month gave time for oil to drain so the monthly start ups eventuall knackered the engine.
Quotes from the OPERATING, MAINTENANCE AND SERVICE HANDBOOK OF A 1964 5.7 V8 GORDON KEEBLE
WARMING UP THE ENGINE
“DON’T start up a cold engine and then leave it idling while you rush indoors to pay a belated farewell to your wife”.
In the interest of minimum engine wear, skip the farewell and drive away. When facing the music on your return in the evening, make a mental note henceforth to adopt a definite sequence of events prior to your morning departure. You will achieve substantially diminished wear from your engine and deserve greater affection from your wife”.