How do you “really” read the oil dipstick?
 

Okay guys, you probably think I've got nothing better to ask, but the truth of the matter that this question comes up to mind every time I check my oil dipstick.
Assuming you are doing this the proper way i.e on a flat surface with engine properly warmed up etc.. Where is exactly the oil line on the dipstick should be? The owner manual, and many other publications, say the oil should be between min and max, but really what would be best reading? right on Max, right on Min or in the middle? Sometimes the difference between the min and max can be more than a quart if I am not mistaken. Thanks.

a little embarassed but ...
 

.... i'll ask anyway. when i check my oil as prescribed above on my 300d t, i sometimes have 'two oil levels' on the dip stick. one one side of the dip stick i will be say a little under full fill. on the other side of the dip stick i may see the oil level as much as 1/2 inch below the opposite side. how to interrupt?

Just so long as the end of your dipstick doesn't fall off . . . :)

But seriously, you want the oil level between the under and overfill lines. The danger zones are being under or over. Underfill is obvious, not enough oil to lube and cool. Too much oil and you run the risk of having your crankshaft turn the oil into a mocha latte topping when it chuns through the excess, which may sound nice, but is worse than having no oil.

I agree. Most dealers don't even perscribe to this practice. The important issue is not to go under or over the lines when the engine is in operating temp.;) That's why you don't fill it to the full line when the engine is cold!

Yes! Overfilling is BAD! The dealer overfilled the crankcase in the C230 SEVERLY, and in no time both main seals were shot. Since then, NO ONE but me changes the oil on our cars. The dealer replaced the seals at no cost, but that does little to restore my confidence...

Actually, it's probably not even pertinent if the oil is plus/minus a quart. However, I kinda like to see it 'just so" also. The owner's manuals always say get it hot and level, and let it sit for a few minutes, so the best possible scenario would seem to have it right at the top of the full mark after it had sat hot for about 10-15 minutes. I know the oil runs down for a pretty long time, cause when I change it, it's still running out a bit after 15 minutes with the drain plug open.

MB engines seem to "like" to be about midway between full and add. Many of us have noticed fairly rapid oil consumption when we have tried to keep it "topped off" and aiming for the full mark.

MmmmI check my oil when the car is cold and leveled. IT has to be hot?! :(

Reading Dipstick
 

Joe,

Not too sure about your 430 but my 300e has two quarts difference between the min. and max. marks on the dipstick. It's pretty easy to check. When changing oil, count the quarts it takes to get to the min (4) and max (6) marks. I also know from experience that the low oil light comes on when the level gets down to four quarts.

MBZ seems to have a pretty durable dipstick unlike some cars with a rubber plug that can be pushed in too far and cause a false reading.

The KISS method
 

Keep it simple and by the book. Keep the oil level BETWEEN the min. and max. lines, when hot, level, and 5, 10, or 15 min's after the engine is shut off. We all love our cars so much that we really need to get a life! :)

No. The oil level will be the same, hot or cold.

But if you top it up, the oil you just added will take longer to reach the oil pan when is has to run through a cold engine. Therefore you need to wait longer to check the level with the dipstick after adding oil, to get a correct reading.

Freestyler

Freestyler, Sorry, But - -
 

- - I strongly disagree. Almost all materials expand when they get warmer. This is especially true of almost all liquids. That's why MB says to check the oil (&, in the past,the transmissiom fluid)when it is hot.

FYI on W124's there was a TSB on corrected oil capacity (maybe due to a few main seals getting blown). at least on the m104 i know that you are supposed to fill it only to midway between min and max...

Re: Freestyler, Sorry, But - -
 

I'm no physics expert. But if what you are saying is right, what would happen to my braking system when i brake hard and my calipers, brake fluid lines -and therfore also the brake fluid got heated up? Would the expansion of the brake fluid block my brakes?

I haven't had that happen yet..

Freestyler

Different fluids expand and contract at different rates. Brake fluid expands very little, but it does nonetheless. However, that does not mean your brakes are "blocked," but pedal feel can be effected by hot fluid. You'll also notice that in the master cylinder, you don't fill the fluid to the lid, but allow room for expansion and contraction, just like in the coolant reservoir.

Your oil level can be quite different at different temperatures. I always check the oil with the engine at operating temp (oil, not just coolant) and let the car sit for about 5-10 minutes.

BTW, H2O is the only fluid that expands when frozen. All others contract.

If oil expands or contracts when hot, and how much at what temperature could be debated for days. From the practical standpoint, I doubt if there is a cup full of difference either way. I don't have a problem checking my oil with a cold engine as long as it hasn't been started. If you start the engine and shut it off cold, it will take thousands of Seybolt seconds for the oil to drain back to the pan. Hot or cold what is important is to pull the stick and wipe it before dipping it again to take a reading. These modern oils will stay at the last highest reading for weeks. You can't just pull the stick and take a reading. A tip for you guys maintaining several cars and wasting time getting the oil level correct after an oil change. To save time when I had a service facility going full tilt years ago, I had my mechanics sprnd extra time and carefully determine the correct amount of oil they put in a car. Then with a set of number punches, they punched ,for example, 6.5 on the dipstick. When the car came back for future service, the mechanic just had to check the #s on the dipstick. Also you troups and troupettes with diesel engines with the filter up above will leave a quart of dirty oil in the car if you don't remove the filter cover before draining the oil.

Peter

When I change the oil in my diesel. I do open the drain plug first, then remove the oil filter cover. All this discussion about when and where the oil should be, and yet no one seems to mention the simple way of measuring oil. Check your oil at the same, everytime. Be it stone cold or warm and sitting for 10 min, just be consistent. This way you can determine if your engine is using oil. When I have added the prescribed 2 gal. of oil after an oil change, I start the engine to get the oil pressure up and then shut her off. I check to see where the oil level is after a few minutes and use that as a reference point. The oil may be "cold", but as long as I check the oil under the same conditions, ie "cold", then I can guage any oil usage.

During May 2000 I bought a 1995 E420. When I did the oil and filter change for the first time, I put in exactly 8 1/2 quarts as the manual calls for. The oil level came up to midway between minimum and maximum. That is the same level it always was at whenever I checked it prior to the oil change.

Before that oil change I was concerned that the car had burned some oil since it wasn't at the max level. Based on this experience with the E420, I now think Mercedes intends for the middle point to be the proper oil level.

Bob

I think mid-level is right. Oil expands when it gets warm, let alone 8+ quarts.

Somewhere on this site I read where someone had continuously filled their engine with oil right up to the full mark and it always went down to about mid point on the dip stick. As I recall they at first thought it was some mysterious leak.

Haasman

i'm with Bob on this. i will check my dipstick on the level
oil on my next oil change.

Thanks Guys
 

I think you all answered my original question. With Bob's answer above and him having the same car I concur with him and My 95 E420 measures at the same mid level point. I didn't think a simple question like this would have generated the interest it did (2 pages) but that goes to show you should never feel bad or stupid to ask ANY question related to cars... we all have different experiences and sharing all that helps the rest of us... like you did here! Cheers:)