My C320 with 98,000 miles recently felt rough while idling at a stoplight. The check engine light came on. The car felt sluggish when I accelerated from being stopped then a puff of bluish smoke came from the exhaust. The check engine light soon turned off and it ran perfectly within seconds.
This car runs so smoothly that it's hard to tell when it's on or off. The rough idle wasn't significant but any vibration is quickly noticed in a car this smooth. I immediately went to a nearby Tuffy. They ran the codes and found a misfire on cylinder one. They also found that I'd run over a plastic shopping bag that was melting beneath the exhaust. They said the puff of smoke was probably from the bag and that it was time to change the plugs and that should fix my problem. I ordered the plugs and went on my way. I drove for three more days with no issues. Then after taking off from a stoplight the exhaust blew an impressive amount of light blue smoke. It was running so smoothly I wouldn't have known had I not looked in my rearview. I immediately pulled over and called the nearest repair facility. Making sure it wasn't overheating I carefully drove it about one mile to have it checked. Cylinder one misfire code was found. They also advised changing plugs. They quoted $600 to change plugs. I declined but did have them change the oil since I was already there and knew it would be coming due soon. They told me the drained oil was thick and dark and recommended a flush. They performed the flush and said to have the oil changed more frequently for the next couple of intervals. All other fluids were normal and at optimum levels and no other issues were found. I drove a few miles without incident until I noticed another small puff of smoke at takeoff. I took it back to the shop so mechanics could see what I was talking about but we couldn't get it to happen again. My local dealership and three other shops checked the usual suspects, found nothing wrong & told me to drive normally and come back if it happened again. Days later, a few minutes after starting it blew a massive amount of blue smoke. I took it to the Mercedes dealership where they spent five hours trying to find the problem. They took the enginie apart and found sludge. They said that sludge was getting into the combustion chamber and causing the smoking. They said nothing had been damaged and the car was in great condition otherwise and quoted me $3000 to clean the engine. The service manager said that chemically cleaning may work and was worth a try. He didn't think driving for a while and trying it would hurt. The only problem with driving it is that it smokes. In an effort to reduce the smoke, I added 6 ounces Bardahl's No Smoke oil additive. Within 10 minutes, the smoking was eliminated the car ran even smoother and gas consumption improved. I just received my Auto-Rx. What should I do now? I understand the fast track application but will it work in conjuction with an additive that prevents smoking? Is it even worth trying or should I give up and shell out $$ for manual cleaning?
Some History: I bought it used @ around 60,000 miles. I have some of the oil change receipts from before I owned it and I change the oil with synthetic when the oil monitoring system indicates. I am not sure why it would have sludge. The sludge isn't solid but apparently thick enough to cause problems. A catalytic converter was replaced a couple of years ago. There have been no other mechanical issues.
The type of driving that you do can affect how long the oil lasts in any engine, synthetic or not. Synthetic oil can last longer in service, some oils longer than others as they are not all created equally. Mercedes has an oil specification such as 229.1 and others that indicate the oil type and quality. Few oil changers adhere to these specs. In addition, the change indicator can cause you to change oil rather infrequently. I like to recommend about half or two-thirds of this interval on these euro cars or about 7500-10k miles as a maximum on these cars, depending on the synthetic oil and type of driving. If you tend to drive just around town and shorter trips such as 10 miles or less, the engine oil will degrade more quickly. As an option, conventional oil can be used, but for shorter intervals. I like the diesel/gas rated oils as they are heavy duty and keep things cleaner inside the engine.
Anyway, get your oil changed and then add approx. 1.5 bottles Auto-Rx. IIRC, this engine holds about 8 qts of oil. Drive the car as much as possible on the highway to get optimum results. Use a 10W-40 conventional oil (non-syn and non- high mileage) or 15W-40 diesel-rated oil (non-syn) along with a new filter. I do not recommend using with other additives, just oil. Try to ignore the smoke as much as possible during this process, however, please check your oil and add as needed. You will most likely need at least 2 complete treatments.
-- Edited by bmwtechguy on Friday 5th of February 2010 08:26:11 PM
As with the previous post, I would recommend that you save the Auto-Rx until you have drained out the oil with the previous additive. It is never a good idea to add more than one additive to the engine sump at one time, or oil change interval.
It is also unlikely that the previous oil additive did much internal engine deposit cleaning. More than likely the previous additive might have swelled valve seals for a temporary fix.
To use the Auto-Rx that has recently arrived at your door step, I would use it with your next oil change. I would also recommend that you follow the Sludged engine application, and not the fast track method.
Step one would be to add the Auto-Rx with a fresh oil change and filter. It is recommended that you run a conventional oil or group III oil motor oil in the correct viscocity for your motor, such as 5W30, or whatever is recommended.
Drive the vehicle for 1500 miles and change out the oil filter. Then continue to drive until 3000 miles have been accumulated on this ARX forified oil change interval.
After reaching 3000 miles, as noted above, drain the oil, change out the filter and run conventional or group III oil for a 3000 mile oil change interval.
On sludged up motors a second Auto-Rx application is normally needed. Merely repeat the process outlined above.
You might try going with the thinnest dino oil that meets your engines criteria. I say that because, the thinner the oil, the more places it'll be able to get to, to do the cleaning.
The heavier the oil, the more crud holding capacity.
Maybe a heavier (but not too heavy) oil for the first clean, a little lighter oil for the first rinse, and then the lightest in spec dino for the final clean and rinse.
As long as she gets enough sustained full warm up events she should be fine. Depending on the sump size, it means that she's not even warm enough for about 15 minutes. It takes some Euro's 40 minutes for full warm up, but most run between 10 to 20 depending on the sump size and if they have oil:coolant exchangers.
Here are the spec'd oil weights. While these are all synthetics, the use of a conventional should be fine for the limited duration of use.
If you're in Southwest Florida, then your temps are fine for basically any of the oils geeaea listed (assuming those are legit oils to use in your engine in NA).
0W-30's and 0W-40's are going to be synthetics, as LIKELY will any of the wide viscosity oils such as 10W-60.
I think 15W-40, 5W-40 (Shell Rotella is readily available pretty much everywhere), 10W-40, or the 30W's excluding 0W would work well. Another one you could try and see about getting is Shell Rotella 10W-30 (here in Illinois, I've only seen it at Menard's home stores).
If you're not doing longer trips where your oil is getting up to temp for an hour or close to it at a time, I'd err on the thinner side of oils so as the flow gets into more places. The difference between 15W-40 and 5W-30 is large when cold (heck, it's large when hot, just no where as far as when cold).
If you're doing around town driving only, you basically are in 5W-30 territory. I saw someone on another thread say that Mobil Clean 5000 5W-30 carries a CF diesel rating. If other dino 5W-30's don't carry that, then that may be a good choice to go with.
If you do do longer trips, maybe for the first clean, going to a 5W-40 like the Shell Rotella could be a good middle ground.
Much appreciation to all of you for the advice. I was afraid that this was a catastrophic problem when the car first showed signs of trouble. I am hopeful now & very thankful that all may turn out well :)
I am now about 500 miles into the sludge treatment cycle w valvoline conventional 5w-30. I was concerned that smoking would resume after the oil change but, thankfully, it has not. It is running smoothly w great performance & gas mileage.
I am altering my normal routes to get as much speed and distance out of each trip. My normal driving routine has been stop-and-go city driving, usually 10 miles or less. I am increasing my highway driving significantly. I will get the filter changed halfway through the treatment cycle. Should I expect to see anything notable in this filter or will changes become evident later?
I think your oil weight choice is the right way to go for the driving you're doing.
In normal driving, it can take upwards of 20 minutes before the oil, not the coolant which the Temp guage is based off of, gets hot.
Auto-RX really works when it's hot, so the hotter you can get the oil, the better. If you do that much in town driving, I'd even kick the overdrive off so the engine rev's a little bit more, so as to make it heat up that much more.
Long highway drives are best though...
As for the filter, sometimes there's tons of stuff in there, sometimes there isn't. Sometimes the tons of stuff doesn't hit until the 2nd Clean and/or Rinse. Although, if you are heavily sludged, I'd expect at least something in the filter.
I think what will become evident, if you track gas mileage closely, is that you'll be getting more per tank. Auto-RX works on the high heat areas first, which is the rings. It's going to clean those out, which is going to increase your compression. When that happens, you'll get better gas mileage as the bonus.
