Subject: 40W oil causing wear problems over 30w?
From: Brian Whatcott

If you were all fired up to reduce your stock hold, you could consider
synthetic. This has incomparably more temperature stability of
viscosity. But besides the expense, it's found to carry the
contamination less well, AND because it DOESN'T go thick as molasses
when cold, the surface run-off is greater.( Of course the initial
oil-passage fill-up and flow is much better too...)

So a synthetic and compatible mineral oil mix 3:1 would fill your
needs for a superior compatible product. Still not cheap though.

Thought of synthetics. But there are warrenty issue with them.

Capt. Bill