dirty oil

[rahkling7]

Just bought a 2004 E320 4matic wagon which came off a lease. Oil is VERY dirty.. obviously lessee did not keep maint schedules up but I got a helluva deal on the car. Question: Aside from changing the oil and using a cheap brand and letting it run for 30 minutes and changing the oil again is there any additive anyone might suggest using to help with the cleaning process or would this be a no no? I know any sort of additive for cleaning is a no no on high mileage engines but this car has 50K miles. If I go the cheap oil route with a quickie oil change should I use a very low viscosity oil which would help the flow inside the engine? Thanks.

[Benzadmiral]

Rahkling7,

There is a product called Auto-RX, an oil additive that you can buy online (in fact you have to): http://auto-rx.com/

Many people here and on the BobIsTheOilGuy site (http://www.bobistheoilguy.com/) have tried it and have tremendous praise for it. Some have posted that they saw no improvement in sludge removal or engine smoothness or gas mileage, but I don't think anyone has ever said the stuff *harmed* his engine. It's supposed to be a gentle cleaner that takes about 3500 miles to do its job -- not a flush which can flake off big chunks of sludge.

I am 400 miles into an Auto-RX treatment on my '97 C230 with 88,000 miles. I can't tell if the engine runs any smoother, but then it always has. I'm due to change oil in early August, and I'll post some commentary at that time, and again after the "rinse" cycle in October.
.

[slk230red]

If it were my car, I would change the oil using a MB oil filter and 0-40W Mobil 1 Synthetic oil. I wouldn't even consider using any type of additive.
Change the oil every 5,000 miles, (or at the FSS intervals if you don't want to spend the extra money), and you shouldn't have any problems.

[david s poole]

the easiest cheapest safest way to clean out a dirty engine is to change the oil every 1000mls three times.been there done that.

[EricSilver]

I agree with using the AutoRX. It is a metal cleaner originally created for printing presses and adapted to automotive use. It will not harm your engine. In my experience, and that of many other users, it performs as promised.

I first used it last December, and continue to use it in maintenance doses. Since my engine was already very clean, I did not experience dramatic results, other than the oil dipstick becoming cleaner and shinier (which suggests the metal parts of the engine are also cleaner and shinier).

Your dirty oil does not necessarily mean a dirty/sludged engine. All the dirt and contaminants may simply be suspened in the oil, as they are supposed to be. If you are concerned, remove the valve cover and have a look. (Even looking under the oil filler cap, to see how silvery the metal parts are, will give you some idea of overall engine cleanliness.)

Frequent oil changes (say 1,500-2,000 mile intervals) with Mobil Delvac, Castrol Tection, or some other 15W40 diesel oil will clean the engine quite well. (Your 30-minute job did nothing.) After that, use AutoRX if you want additional assurance, or for general maintenance.

You are correct to use the lowest feasible viscosity, to make sure the oil flows as freely and thoroughly into every nook and cranny. In the heat of the summer, that means a 40-weight, and Shell Rotella 5W-40 is great if it does not get too hot where you are. Otherwise, you can't go wrong with Castrol 10W-40. In the winter, 10W-30 will do just fine.

[Peter Guenther]

Just have a dealer change it with the proper oil,filter and do it a few times, in short intevals. You will get it clean without using fushing agents. Your chances are much better if you loose an engine if you did not mess around. I wonder if it came off lease why the dealer took it to the auction or sold it cheap it does not compute.
If it was abused, the lesee usually gets punished

[compress ignite]

Mr. Poole,the rouge SLK and Mr Guenther have the only safe options/answers.

If it was sold with dirty oil ... it deserves some TLC. Mobil 1

(AND before you change, get an oil sample sent to a lab with the old oil
to get a baseline for the lab's comparison).Then dump the oil and filter at 500 miles.After taking a "Clean Catch" sample of the 500 mile Mobil 1.

This will tell you more than you ever want to know about the engines health!

'Putting ANYTHING, EXCEPT OIL in the crankcase is just begging for TROUBLE!

[EricSilver]

Originally Posted by compress ignite

'Putting ANYTHING, EXCEPT OIL in the crankcase is just begging for TROUBLE!

Since there is no such thing as straight oil, that is impossible.

Mobil 1 is loaded with sythetic esters & additives that make perform as it does. AutoRX is made from naturally ocurring esters.

[rahkling7]

thanks for the advice... now for the really dumb questions.. vehicle came with no books. Obviously I am going to have to acquire some. In the meantime wife will need to take vehicle on overnight next week. Was planning on doing oil change myself. Car has no traditional dipstick... all electronic correct?...assume oil filter is located in screw off canister near front. Gas cap states premium fuel only? Finally, how many quarts does she hold? Thanks and please excuse the stupidity my 95 E300D and my Subaru aren't this complex.

[EricSilver]

Since it is your first time, the best thing to do is take it to a dealer or MB tech for the oil change, and observe how they do it.

[G-Benz]

If the PO lapsed on oil changes, there are probably other service intervals that were ignored as well...like air filter, coolant and brake fluid transfusions, etc.

Check with the dealership for info on the recommended services to be performed up to the current mileage on the vehicle, and get those done as well.

[brewtoo]

You don't have records to verify when things were done.

Just curious, why do you think it was neglected? Oil is black by the time it gets changed anyway, so how do you determine that your oil is "dirty?"