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.