Ive seen several posts about how seafoam can be used to flush out engine sludge? how exactly is this done? id like to make sure my a4 doesnt have sludge of any kind. thanks

 

You have an 05. If you have used syn oil and the large filter you have nothing to worry about. It was mainly the people using either/or reg oil and small filter that had the sludge problem.

As to how seafoam works, it basically increases the temp in the engine/oil and breaks down all oil and carbon deposits

 

never hurts to do on 1.8ts.... basicall i did half a can of seafoam added to my crankcase..... 50 miles of driving. then oil change. you can use it as a vac line treatment and a fuel system treatment as well

 

^^^. I do it every 25k miles, 1 can w/ full tank of gas, half can into the oil crankcase (where you pour oil) and the other 1/2 can is sucked in through intake manifold vacuum, let it idle for about 15 mins (gonna be alot of white smoke), then drive around for about 50-75 miles and do an oil change...

 

Or you can do a more aggressive slude treatment called Auto-RX http://www.auto-rx.com/
Its a 3 step process, first change oil (mind you, they recommend using conventional oil cause synthetic can mix chemistries with the auto-rx),and filter, add 12oz of auto-rx. Drive for 2500 miles, change oil and filter again (can use syntentic this time, do NOT add any auto-rx), drive for 3000 miles then change oil and filter again with full syntethic... done... They recommend if you have over 100k miles to do the process again. In order to keep it from gaining anymore sludge, add in like 3oz every oil change.