My “solution” is that if the engine has not been run for a week or more, remove the spark plugs, disconnect the ignition LT lead and spin the engine on the starter, just until the pressure gauge “registers” a few PSI.
Then, by replacing LT lead and plugs, I find that on start-up, the pressure gauge moves to around 65-70 PSI instantly – the colder it is, the higher the initial pressure. This way, I am reasonably sure that oil is getting to all of the important bits. So far, so good.
If anyone knows of an equivalent filter to the GFE121 that does not leak back, please let me know.
Follow up thought:- When I was still working, we had this “drain-back” snag on several aircraft which were often not flown for a week or more, so we rigged up an oiling system that could be coupled into the oil delivery pipe – which meant cowls off so took a bit of time – then we pressure fed the oil into the “plumbing”, pulling the engine through as we did (Make Sure The Magnetos Are OFF!!). It was most noticeable on engines with a gear type oil pump and relatively high hours running time, an overhaul (expensive!) always cured it.
Does this indicate that my MG engine may be due for overhaul or replacement? – I had better start saving!
Keep safe and I’ll send some more technical thoughts in July.