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Why not use a good quality synthetic oil, instead of worrying about oil temperature. Such an oil will withstand far higher temperatures than your engine can produce (and still run) without carbonizing or other breakdown of the lubricant.
Actually, of more concern (with synthetic, because it actually lowers lubricant temperature) would be ensuring that the oil gets hot enough often enough to boil out any condensation that could accumulate acids and other combustion contaminants.

But since you've already put in your gauge, you should try to calibrate it against some reliable measure such as with your sender immersed in boiling clean water -- gauges are notoriously inaccurate sometimes, and resistances in the wiring of the gauge also introduces additional errors. The next time you change the oil, take a pot of water that you've been boiling on the stove, bring it over to the car (place under it), and use a propane torch to keep it simmering while you drop the sender into it (use the original sump plug to keep oil from dripping). This way, you'll be checking the gauge's entire circuitry intact.

Good luck.