300E Oil level is nuts!!! - PeachParts Mercedes-Benz Forum

mike690003 · #1 08-04-2003, 10:33 PM

Hello Board,

After idling my car for about 20 minutes, the "low oil" light came on. I inspected the oil level while the car was on and it read below "min" level. I cut the car off and I looked under it for a major oil leak. After about 5 minutes of searching and finding nothing, I re-checked the oil level. All of a sudden, the oil registered in the middle between "min" and "max". What could be the cause of this?? Could this do damage to my car??

bobbyv · #2 08-04-2003, 11:19 PM

the level is below minimum when the engine is running because it is being pumped throughout the engine.

the oil level should be checked with the engine off, and after about 5 minutes of turning it off, to allow all the oil to drain back to the reservoir, at which time it should be measured. Sometimes, the oil level lamp comes on even if the oil level is between the Min and Max markings - it may be a faulty oil level sensor.

JimSmith · #3 08-05-2003, 12:13 AM

The oil level light is a warning lamp and as such it comes on when the level gets below the midway point between the marks on the dipstick. It alerts you to check the oil.

The light cannot come on until the oil temperature is approximately 80*C and in my vehicles once it comes on it goes off relatively quickly. As the level continues to drop the light stays on longer. When it stays on pretty much constantly my cars take a quart of oil. Most of them will be at the point of needing an oil change at that point so I change it. If the level went below the minimum level to light a dash light, the color would be red, and the motor should shut off.

Hope this helps, Jim

mike690003 · #4 08-05-2003, 12:46 AM

So I should ignore the light?? It was only on for about 5 seconds. I changed my oil 2 weeks ago.

JimSmith · #5 08-05-2003, 01:05 AM

mike690003,

I think it would be best for you to find a level spot and, after the car is warmed up, check the oil using the dipstick. Pull it out, wipe it off with a clean cloth or paper towel, then insert it again and pull it back out to read the level. Once you read the level, note the mileage and then, assuming the level is between the two marks on the dipstick, go ahead and drive. When the light stays on, read the oil level again, note the mileage and either fill it with another quart, or change the oil again.

Keep track of the mileage when you refill and when you check the oil level, and when you change the oil. This will help you get a handle on your rate of oil consumption. If the level falls below the minimum mark, you should add oil to bring it above the minimum level. Most of my cars take nearly two quarts to go from the minimum level to the full mark. When you get the light and the level readings coordinated and quantified in your mind you can respond to the warning lamp as you feel is appropriate.

Sometimes the manual calls for a number of liters to fill the engine, and we have quarts, so you end up shorting the engine fill slightly. This leads to a quicker oil level warning unless you make up the difference.

I did not mean to suggest you should ignore the warning lamp. I am sorry if I confused you, I was trying to note it does not indicate the oil level is below the safe level, since it is yellow. It indicates you should check the oil level to find out where it is as the level has dropped from a known safe level. The oil level check is supposed to be done as noted in the earlier post by bobbyv. Once you have gone through this a few times you will have calibrated the light to the dipstick level and be in a position to wait to respond if that is what is called for, or add oil at the first flicker of the lamp, if that is appropriate based on your car. Good luck, Jim

#6 08-05-2003, 03:13 AM

Quote:

Originally posted by mike690003
I inspected the oil level while the car was on

oil should be checked with the car off.

#7 08-05-2003, 07:26 AM

You should check oil on level surface with engine off as JimSmith described. I would fill it to the full mark as measured under these conditions. I would never remove the dipstick with the engine running.

Cars have operated quite well for almost 100 years before oil level warning lights. Rely on the dipstick and be happy.

Good luck,

dakota · #8 08-05-2003, 09:54 PM

I do not fill the oil to the max mark. Halfway between the min and max seems to be the optimal. If you constantly fill to the max mark, you may find that your oil consumption goes way up. Mercedes Technical Service Bulletin 00/57A dated Nov. '95 talked about this.

And I find that the best time to check the oil is in the morning before you start the car. You will have a consistant base point this way....oil level can change dramatically depending on oil temp and water content in the oil.

However you decide to check your oil, I think doing it in a consistant manor will give you a better indication of your consumption.

Also, sometimes that sensor (oil level) starts to go bonkers. Some have luck cleaning it, some have luck changing to a synthetic (although most oils now-a-days keep your engine internals pretty darn clean), some people have to replace the sensor.

#9 08-06-2003, 07:11 AM

Running the oil a little low is a patch for decreasing oil consumption in engines with a problem. If your engine does not use oil, run it at, but not above the max mark. My 103 doesn't go down hardly at all between 3,300 mile changes, so I run it at max.

If your engine IS using oil, then running it in the middle might offer a slight amount of help.

Good luck,

400E · #10 08-06-2003, 08:10 PM

I think it depends on the particular engine. Once I became familiar with the TSB mentioned above, I stopped trying to keep my oil level at the "full" mark. When I do an oil change, I aim for the mid-way mark and do not need to add oil between 5000 mile changes. When I tried to keep it "full" it would use oil until it hit the mid-way mark anyway.

From my reading on this and the Ritter list, this is a very common phenomenon with MB engines. They seem to "like" to maintain a middle-of-the-road oil level. Mine certainly has been doing this since it was a pup.

#11 08-07-2003, 07:30 AM

I guess I've been really lucky with all my MB engines, I've never seen this at all.

One of my diesels went through a period of using so much oil that I would not have been able to tell the difference. The other ones and ALL the gas ones could be filled to the MAX mark and they would just stay there.

Have a great day,