From Haynes, Diesel oil levels, how do you check yours
 

A member asked a question at Haynes that I think I have seen mentioned before but can't remember where.

He gets differing readings on his dipstick depending on when he checks the level, and even differing levels if he repeats the same check a few seconds later.

I can't say I have noticed this behavior on my CDT but otoh I only check the level once a month if that, as the car does not use any oil ever, and that is always on level ground with a cold engine normally several hours after it had last been used

Is there a right or wrong way/time/engine temp etc to check the level?

Good ol' Haynes manual says to check oil when engine is cold (or wait 5min after switch off). This is because when the engine is in use, oil is in circulation (obviously) and when you switch off the oil can still remain in the upper engine components (leading to a lower-than-actual reading)

Thermal expansion (albeit, only slight) can be important with hot oil too (not to mention personal injury risks....)

As you suggested at Haynes, sludge could be causing inaccurate readings if the sludge is blocking the pipes, especially in the narrow pipe the dipstick goes in.

Snipped you twos last two posts funny but inapppropriate, you can get off the floor now Simon :)

Anyway I mentioned sludge as a possibility as that could cause higher than real readings but is that a real possibility?

Quite right about posts, fair enough decision :)

As for sludge.... there would have to be a fair amount in there to cause inaccurate readings. In fact, if there were that much sludge you would start to question when the last oil change was...

What other mechanics are in the derv engines? Y'know, like reservoirs or places where the oil can settle?

Keith

The dipstick appears to have a tight air seal to it. You have to remove the dipstick, clean it, pop it back in and then take a reading.

Not that it uses any oil. I have only put in 0.5L in 55k miles between services.

55K between services :panic:

maxi_crawf

That's not quite what i meant!

I mean from new, apart from oil changes, I have only used 0.5L of oil.

When I take the dipstick out the oil on it smears up the dipstick hole, wipe then reinsert and the reading is always about 4 inches past the top mark.

Mine doesn't do that, interesting. Or, is your oil over filled?

Thats partly the point of this thread although 4" is a bit extreme I have seen it mentioned elsewhere and the guy at Haynes prompted me to bring the issue up again.

I agree with you Rich I reckon a combination of capillary action and the fact the stick is fairly airtight is causing oil to rise up the pipe on the move

So pull the dipstick, clean it, allow the contents of the tube to settle then check may give a bit more accuracy.