[Latitude 28]

With this topic opened up, I am on the search for a decent synthetic 75-90w oil. Can I safely assume if it's synthetic, they are all the same? (brands) Also, would it be worth going with a 75-140wt oil?

Simon,
I have used Mobil One synthetic oils in my cars for years with no extended intervals and a oil change a 5,000 miles.      About two years ago did some updated research into the current brands of synthetic oils.  Came across some great reviews on Walmart's Super Tech oils.....its cheaper probably due to a low marketing budget.  A friend of mine and I switched our vehicles over to Super Tech (he also used Mobile One with a 5k interval oil change).  I have done four oil changes with an oil sample taken at least twice with no detectable difference compared to Mobile One.  He has taken oil samples as well with the same results.  Having said all that, the Walmart Super Tech Synthetic is made by Warren Oil company and they probably make oil for several synthetic brands out there.  The ST 75-90w synthetic is $10.42 a qt. compared to Mobile One at $14.98 at walmart.  Cant say if the 75-140w oil would be any help to normal operating temps.......might be of some help to someone living in a desert:-)