M50 has sludge ...normal?

[fujioko]

Hi again,

In another thread that I started, I was seeking advice on pulling a M50 engine out of my e34. Many thanks to all who lent an opinion and advice. The M50 pulled out with minor collateral damage to a silly plastic part. The low mileage M50 dropped right in with the help from the ten year old.

Anyway as I’m putting the e34 back together I decided to swap the cam cover from my dead M50. I pulled the cam cover off the “low mileage” M50 only to discover a lot of crud and sludge. Something I wouldn’t expect on a modern engine with modern oil. The sludge build up certainly isn’t as bad as some of the older American engines I have worked on, however it seem out of place on this engine.

If this engine is truly “low mileage” (110K) then perhaps it did a lot of short trips and idling??.

The story on the "low mileage" engine was it was pulled from a wrecked 5 series. I paid $600.00 for it.

Anyway my dead M50 with 275K was super clean and only had mild varnish and stains.

I guess I could clean the crap out or just leave it and hope a few oil changes will start dissolving the gunk.

Any advice?

[Blitzkrieg Bob]

Over the next few months, and use a detergant additive to help break the sludge looose.

[winfred]

that's just the results of following the bmw oil change guidelines, you outta see the newer motors when they changed the recomended oil change from around 10k miles to 16k miles, even if it is synthetic oil i don't think the filtration system can handle the load, you wanna talk filtration and oil life some of the guys on the cummins diesel board i am on are running over 20k miles on dino oil and over 50k on synthetic, using bypass filtration, regular filter changes and oil analisis to track wear/oil break down

[joshua43214]

Winfred is right, this is just normal with the long interval on oil changes. So, if BMW says its ok then its fine right? maybe so, but I dont like it. Excessive sludge build up can slow the rate of oil return, reducing the amount of oil in the sump at higher RPM, I have never seen a BMW suffer from oil starvation, but I have seen other cars do it and I am sure someone out there has. so I change my oil more frequently. If you have a really heavy sludge build up, I would not recomend using a flush, rather change the oil every 1.5k with regular oil or every 3k with synthetic until its all clean. should take about 3 oil changes. I change mine when the service indicator is 1/2 done so I wont have to reset it.

[SRR2]

For another approach, browse over to bobistheoilguy.com and search for "autorx".

[Russell]

I am now in the final "rinse" phase after two treatments. I "believe" the car runs slightly stronger (cleaned ring packs). I do know the engine seems quieter. I know that when the valve cover was removed about 35,000 ,ils ago the engine was fairly clean as I changed the oi/filter with synthetic every 3-5,000 miles. I suspect it is slightly cleaner now.

FYI, I tore a filter apart during the cleaning process and found small amounts of dark sludge like particles in the pleats. I recommend Auto-RX as I think it gently cleans your motor with no harm.

For another approach, browse over to bobistheoilguy.com and search for "autorx".