I figured if the valve cover was that bad, the inside of the motor had to look pretty bad too. So I changed the oil and filter and ran a quart of MMO (Marvel Mystery Oil) in it for about 500 miles. I then changed the oil again, using some high dollar crankcase flush I bought specifically for BMW's. When I drained that oil, it was pretty dirty for only being in there for 500 miles.
I refilled with new oil and a filter at the viscosity recommended in the owners manual. When I did that, I noticed a very loud lifter noise on start up that would go away after a few seconds. I figured it was just a sticky lifter.
As the weather turned cold, the duration of the lifter noise became longer and louder. I decided to run some lighter weight oil for the winter months and it helped with the lifter noise. It was still there, but not too bad even in really cold weather (at least for where I live).
The car wasn't being driven more than about 3 to 4 hundred miles a month by my son. So this oil change lasted almost a year. I started driving it to work when he left home for bigger and better things instead of driving my SUV and putting so many miles on it. Some days it wouldn't make any noise, some days a little.
I decided to do some research on ways to possibly get rid of the noise. I found some interesting message board posts on various boards that talked about MMO and another additive called Auto RX. I had tried the MMO and it didn't seem like it had done much before. The Auto RX (ARX) had some pretty convincing testimonials that I was reading. I looked for negative remarks but really couldn't find any so I decided to try it for myself. I ordered enough to do two of my vehicles and will keep a log of what happens with my 93 E34 for all to view.
Today, I received my order of ARX and put it into the cars I wanted to treat. Since there was no reason for me to open up the valve cover on the 93, I did find some varnish build up under the lid to the oil filter housing and inside the oil filter housing (see attached pictures). The ARX claim is that it will removed these harmful buildups of sludge, varnish and other contaminants "layer by layer". I will take more pictures when I change the oil to flush out the treatment in 3K miles. I'm hoping that there will be an improvement in performance and also in mileage. That's what they claim. On this car, they state that it will need to go through two complete treatments to get the best results due to the mileage.
If I notice anything performance wise or mileage wise, I will make note of it during the 3K mile treatment phase.
Here are the pictures I referred to:
This one is the underside of the oil filter housing lid
This one is the inside of the oil filter housing
