Another question....What is the best type of oil for the 1.9?

I live in Texas and its fairly hot all year round. It has been in triple digits consitently this month and my MPG seems to be low. Ford reccomends
5/W30-10/W40. I would think that during these hot four or five months that 20/50 would be offer more protection. How much would the mileage be affected by not using an effective oil grade?
Thanks
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I'd go with synthetic (Moble1), 10W40. I would doubt that the operating engine oil temperature is much higher when the temp. outside is 120 degrees vs. 60 degrees. The thermostat should keep the operating temperature about the same (I would imagine the temp. of the oil might be like 20 degrees hotter, but I doubt that has any significance when it comes to the lubricating properties). And even if it is significantly higher, the synthetic will break down less than conventional oil.
Jeff

that
affected
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I'll try it. Synthetics will go more miles? I have heard that you can change after 5,000 instead of 3,000. My engine seems to be running cool at the lower end of the operation temp.
Thanks for the input

triple
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Mobil 1 recommends that you change the oil at the upper end of the range that the engine manufacturer recommends (so in this case, probably 5,000). Other synthetic oil makers say that you can go longer, like 10,000 or 20,000 between changes. Personally, I am not sure whom to believe.
Jeff

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