Have pictures of Oil change procedure? Which two bolts?

The plug at the bottom of the engine sump is for access to an inner plug which is on the oil pump holding the pump spring which controls the oil pressure. This inner plug is not for any pressure adjustment as it is tightened against its copper washer (to the pump body). Any adjustment (change) of the oil pressure would require use of a different spring, having higher or lower spring rate.

 

Of course you're right. Thanks for the correction.

 

I found a good picture of the pump which clearly shows the "inner" (pump spring holding) plug and its copper washer.
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There is no big issue if this plug is accidently loosened or even completely removed. It should just be tightened back with a new copper washer (and making sure that the fallen out spring and the plunger above it are correctly re-inserted).

 

Thank you all. Will use the correct, bottom plug.