lundgrji, that is alot of miles on BUGOIL in a short time, what kind of oil have you been using and distance between changes? Any hassles related the engine during that time? Just curious as that is the most mileage I've seen posted on a new version TDI engine.
My wife drove BUGOIL 135 miles a day for work up until a couple months ago, whereupon she found a job locally. A few long distance trips also piled the miles on.
I had been converted to synthetic oils prior to purchasing the bug, so from the first oil change I brought Castrol Syntec or Mobil 1 to the dealer. A couple months ago I stumbled onto the endless oil debate threads and decided to switch to Mobil Delvac 1.
Oil is usually changed every 5-8K miles, and I once let it go for almost 10k.
I've had some professional experience with engine flushing systems, and the damage caused by varnish and sludge deposits. Basically, hot oil breaks downs, leaving varnish on the internal engine components. The varnish reduces heat transfer from the engine components to the oil, resulting in higher oil temps, more varnish formation, and so on. The oil passageways can also be obstructed, reducing oil flow volume. Your pressure gauge will the read the same or higher, however.
I perform my oil changes as follows: Add 8 oz of Gunk Engine Flush and let engine idle 5 min. Remove drain plug and drain pan. Install drain plug and add 4 qts of inexpensive, non-synthetic oil. Drive vehicle for 10-15 minutes, with plenty of hard braking, cornering, and accelerating to ensure the oil sloshes around. Remove drain plug and filter and put in the new filter and oil. It takes 1000-2000 miles for the oil to get black; it used to get black immediately after changing the oil when I did not flush the engine.
Also, I've cleaned out the intake manifold area at the EGR butterfly valve twice. It gets very plugged with black sludge. I wonder what the rest of the intake and valves look like. I'm looking into a way of cleaning the intake by injecting a fluid while the engine is running. Just flushed the intercooler too; when I removed the bottom hose oil drained all over me, as if removoing a drain plug.
The only engine concern was the faulty glow plug relay. Otherwise, it has been totally trouble free. I'm not looking forward to having the VW Dlr replace my timing belt, as it will be their first TDI bug. If I do it myself, and there is any engine problem that can be related to the belt replacement, I fear the engine warranty might be in jeopardy.
It's an awesome car. A K+N filter is on order. The Wett chip is tempting, but my wife's last car (and the reason we know own the bug), a strong running Volvo 760 turbo wagon BLEW UP big time, spewing the con rod onto the interstate. This happened right after my tuneup, K+N filter, flowmaster muffler and timing advancement to the top end of spec. I'm generally nervous about adding more stress to an already force fed, highly stressed engine. I might get over it, though.
Because a diesel lacks a throttle valve, I don't think that a thin coating of gunk is a problem anywhere in the intake system EXCEPT for the inside of the intercooler. A partially blocked EGR valve is a good thing, in my opinion, as long as it isn't bad enough to trigger a fault code. I'd be extremely careful about spraying any kind of solvent into the intake while the engine is running. You might damage the engine.