Is it possible to pull out the oil dipstick with the engine running in a BMW?

BMW driver question

For several months I have been driving around Poland in search of my dream Z3. I test all the copies as much as I can. Among other things, I conduct such a test (which has worked well in the cars I have bought so far):

1. I start the engine.
2. I wait a while, listening to see if it runs evenly.
3. On a walking engine, I unscrew the oil cap/remove the dipstick.

At this point, in most of the specimens I looked at, the engine’s revs began to ripple severely. In some, it was possible to notice the dipstick sucking/puffing with this operation. In my previous cars, such a symptom would indicate a lot of engine wear, but after reading many BMW fan forums, I found information as if “in this engine it is supposed to be so”.

Does the symptom I have described really indicate proper engine operation?

If the symptom is not correct, is the cause a minor malfunction, or is it indicative of serious engine wear, however ?

The problem affected a BMW Z3 Series model , but it also occurs in other models.

BM Cars service response

Unscrewing the oil filler cap or removing the dipstick while the engine is running will always cause the engine to rev up and blow out small amounts of gas. This is a normal symptom that does not indicate an engine malfunction.

We suggest a thorough inspection of the car you are looking for before you buy it. We offer full computer diagnostics, checking the condition of the suspension, steering, brakes, checking for signs of auto body repairs, measuring paint thickness, checking the vehicle’s service history and verifying mileage.

We invite you to take advantage of our service.

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• High oil consumption in BMW – what is the reason and what is the norm?
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