How long should you run with an engine flush

[Mas (UK)]

before draining the stuff out of an engine?

The messy sludge I found in the valvetrain when replacing the valve cover gaskets a few weeks ago was pretty shocking. I've taken some pics and will try to put them up here for you to see soon - anyone easily scared speak up now!

What do engine flush products actually contain anyway? Do you drain all existing oil and fill up with the engine flush or what? Any suggestions are very welcome.

Cheers,

Mas

[632 Regal]

Ohh mann... I personally wouldnt use any kind of oil flush or additive.

Tried this with a relitives car many years ago and all the sludge clogged the oil pickup and fried all the main and rod bearings.

[Russell]

What brand of flush are you using? Apparently from some reports, they can be very harsh solvents and should only be run/idled for only a few minutes then change oil and filter. I would ask around at BMW dealers and independent shops regarding their recomendations

Here in the US there is a product call Auto-RX (do a google search) that is a metal cleaner intended to gently clean your engine. Basically it is a 3,500 mile two step cleaning/rinse product. Change oil (any oil) and filter, put in Auto-RX and drive about 1,500 miles. then change oil and filter (no synthetic this time) and drive 2,000 more miles to "rinse" the remaining contaminants out. Then change oil (oil of your choice) and filter and you are done. However, do this process twice if you have over 100,000 miles. Some people claim it is "snake oil" others say it works very well.

I am currently 500 miles in the first phase. No problems car seems to run great.

Good luck

[Russell]

darn- I was hoping for informed/uniformed comments

[High Compression II]

If there is a LOT of deposits, then probably either a cheap poor quality(2.50 at Asda type) oils have been used in the past, or the change intervals have been ignored. With todays oils, even the cheaper good make variety, deposits dont accumulate, unless the oils are not changed when recommended.

As the previous guys have said, be VERY careful with any flushing agents, they do disloge the gunk, which then can block the gauze pick up in the sump, then no or little oil pressure and wrecked bearings. Did this myself around 10 years ago on a Honda.......

Having said that, For Diesel engines, a litre of diesel fuel in the lube before dropping and changing works wonders, BUT I wouldnt use this method on a Petrol motor!

[Kalevera]

You know, I've been saying this a lot recently: using BMW synthetic oil and changing it according to the lights results in a gunked engine. And I'm not the only one to say it -- we routinely trade pictures of sludged engines on tech group. People still don't seem to get it.

In fact, I pulled apart an M52 last Friday that had a layer of sludge in the pan, and the pickup was covered, as well. Go in my directory (http://www.bimmer.info/~lowell/) and look at that PDF. Also check out that E38 pan picture.

In my car, I've run detergents (MMO and the like) for 500 miles with Delo 400, a chevron diesel oil with a good detergent package.

best, whit

[High Compression II]

The extended service intervals on modern cars demanded by the general public are partly to blame for this.
When BL introduced this in the early 70's in line with their competitors LOTs of engines suffered badly, It was blamed on the oil at the time, Remember 'Super Visco-Static? I think this stuff was made by BP--There was nothing actually wrong with the oil, It was just expected to go for longer than it would.

Generally, I tend to throw out the makers advice/recommendations, and change oil at every 4K, and filters every other change, Seems to keep the crud away, the valve gear in most of the Mercedes vehicles Ive owned has remained clean, with just light brown coatings, more a stain than a coating. The MB Diesel engines running a good quality semi-synth detergent oil remain totally clean, The head doesn't get quite as hot as its petrol relative.

This black goo forming issue was VERY bad in the 2L 106 series MB petrol engine ('85-95 W124, and late W123 series 2L) as the head runs quite hot anyway, with a lot of oil circulation for the OHC and valve train, Coupled to the fact that for some idiot reason MB used a very small oil filter on this series motor, which if not changed, will actually block and starve the engine bearings of oil!--Thats the only engine Ive seen that happen on!

Car design these days is done by Accountants unfortunately and driven by the Market, rather than Engineers, hence the long service periods. After all, the vehicle isnt really expected to hit its tenth birthday with the average ownership/service/care is it?-

Vehicle makers are in the buisness of selling cars, therefore if they last too long, they are soon out of buisness!

A really cheap quality oil changed at every 3K is far better to my mind than a Super Mega Expensive synthetic bells and whistles oil changed every 6K--After all, the quantity of contaminants present in the oil are dependant on how long the oil is used, regardless of its pedigree!
True, a poor oil will degrade faster than a premium oil, but its the contaminants that mostly cause the damage. A lot depends on what 'Additive Package' has been added to the base-oil as to how long it lasts/degrades, rather than the base-oil to which its added.
That oil you buy, isnt just oil. Its a huge concoction of different formulations each directed at a specific shortfall in the base-oil.