3+4: You need to figure out if its a flow or pressure problem. First check coolant level, then replace thermostat....go from there.

6: Use Diesel grade oil -- 15-40 Rotella-T is the usual favorite and can be had cheap. Change intervals are debated too, but the more often you change the better -- period. I personally do 3k no more than 4k between changes as I'm planning on keeping both my cars until the day they give up.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k