I'll try to make this brief, but it's an ugly story any way you cut it. My daughter was attending the excellent BMW Street Survival school a couple of weeks ago. (http://www.streetsurvival.org) After a couple of hours doing the various obstacles (nothing high speed, lots of slalom and quick stops), the oil pressure light comes on. The instructor tells her to pull over and they let the car sit for a couple of hours. The oil level is fine. Upon starting things are fine for about 30 minutes, then the light is back on and some valve noise is evident, so the car is retired for the remainder of the event. We attempt to drive it home, but get only a couple of miles before opting for the AAA tow. I could hear significant noise at that point.

The car is a '95, non-turbo. I've babied that car since the beginning. It now has 126,000 miles on it. Oil & filter have been changed religiously every 3,000 - 4,000 miles. It has had Mobil 1 in it for over the past year (2 oil changes) and for the prior 6-7 years it has had only Castrol semi-synth. The flame trap has been cleaned or renewed at every change.

It goes to the indie shop and they listen to it and are convinced at least one rod bearing is shot. I give them the go ahead to put in a used motor replacement. A donor'96 motor with 88K on it was found and "swapped" out. I just got the car back today and it runs well.

The techs at the shop removed the old oil pan, and that is the true subject of this post. Their first question to me was "Did you change the oil any more frequently than every 10,000 miles?" The amount of sludge and caked on buildup in this motor is unbelievable. You can see for yourself:

http://tinyurl.com/32tfvz

The pictures don't show it well, but you can see small shiny bits of aluminum in the puddle.

The shop's opinion is that the oil sump got clogged with sludge and starved the pump. Where did this sludge come from on a (seemingly) well-maintained engine? Their main theory is my use of the Fumoto Valve. You'll see in the picture how the valve output is actually about 1/2" off the base of the oil pan. They speculate I never got a complete drain during oil changes. I would counter that I always used ramps, giving the Fumoto a slight downward bias. Perhaps not enough.

The other prevalent theory is that the switch to Mobil 1 actually caused the caked oil to flake off the crankcase, due to its high detergent content, which clogged the oil intake tube.

Why did I switch to Mobil 1? For almost the last two years the car has been driven mostly by my daughter back and forth to school, which is about 1.5 miles each way. It would get some highway time on occasion, but not every day as it had been getting for the first 11 years of its life. I thought the Mobil 1 would give superior protection on these short trips, especially in winter.

So my question to you all is, what do you think was going on in this motor?

Regards,
Doug
--
'94 945t; '95 854 base; '05 S80 2.5T