Cold starts on straight 40 wt is, in my opinion, not a good thing. I would think you would be alot better off using a multigrade (20w-50 wt), high quality oil. Excessive clearance between the bearings, crank, etc and oil pump can cause the low oil pressure. What kind of frequency has the oil been getting changed at?
Ya'll please don't let this start another oil thread - it is just my opinion.

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Jim