Brother of The Benz,Justin Morrison
Reaping the benefits of Synthetic oils won't occur overnight.
There are varnishes, carbon and sludge deposits that have been aquired over the miles and the synthetics cleaning and detergent capabilities take time to remove this crude.
I was a diehard to changing to the man made oil.
At 150,000 miles the change was made.
My 103983 engine in my 1987 300E had never gone more than 4000 miles between changes using dino oil.
My engine didn't need the time to clean some of the left behind stuff.
Now at 177,000 miles, there are NO oil leaks and NO oil consumption.
Those who experience these problems must have been holding their engines together with stuff.
Justin, make your change to 20W50, set your intervals at no more than 5000 miles(filter too), get a pump to change from the topside.
Look at http://home.earthlink.net/~asherson/Don
and save yourself some moola.
Happy Trails Beep Beep from The Spiderman in Houston!!!