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Dipstick Accuracy

1351 Views 22 Replies 10 Participants Last post by  ColdCase
Whenever I first pull the dipstick the oil level always shows low but if I replace the dipstick and withdraw it again, the level is too high. If I leave the car for an hour or so then check the level again, it still reads too high.
If I check it at daily intervals, on the first pull of the dipstick it always reads low, on second and subsequent pulls it always reads high.
Just to be safe I added 2 litres of oil but after leaving the levels to settle overnight, I still reads low on the first pull.

Even though the cars not due for an oil change, I plan to drain it off and fit a new filter, then fill up to the manufacturers specification.

Has anybody else experienced this weird problem?
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· Registered
7 Posts
I would never add a quart just to satisfy the dipstick. If you change the oil yourself and you use the recommended amount (7.7 or 8 quarts in your case) wherever the oil level is on the dipstick, then that is your full line...
I understand what you are saying. Here is my current thinking on this - what do you trust - a written specification or a physical measurement? Obviously, 8-quarts is satisfactory as that is what the factory recommends and warrants. But, what if you could put in another quart?

What is the downside? If the oil is too deep in the pan, the crankshaft will catch the oil as it rotates and whip it into a frothy frenzy. That's probably not real good for the oil. In addition to impacting efficiency (mileage) from the additional drag, there is maybe the possibility of sucking air in the sump pickup and loosing oil pressure in an extreme case. All of these are reasons why racers use windage trays (my understanding). Typically engines are designed with some headroom between full on the dipstick and contact with the crankshaft.

What is the upside? My opinion - the upside of another quart of oil would be that, with an additional 12% oil capacity, the oil would be doing that much less "work" - the oil would be cycling from the pan through the engine fewer times. There might even be a small impact on oil temperature, but I'm not convinced on that.

As a point of reference, the oil capacity for the Mercedes V6 3.0L turbo diesel used in the Sprinter is 13 quarts. The Sprinter 4-cylinder 2.1L diesel takes 12 quarts, Obviously a different engines, but most diesel engines are designed with high capacity oil sumps for a reason.

I'm becoming less of a rule follower as I get older. If the engineers at VM Motori were capable of designing a dip stick that accurately represents the oil level in the engine, then I see no downside to adding a additional quart to bring oil level up to the full line. Just my opinion.

· Registered
258 Posts
I hear what you're saying Willy. I just can't get the early WK2 hemi dipstick fiasco out of my head. Everyone was adding oil to bring up the level on the dipstick and in effect over filling the crankcase, only because the incorrect dipstick was installed on the assembly line.

If I could find the absolute correct spec in the service manual or owners manual I personally would use that as my fill level/amount. I think finding the correct spec is the whole issue here.

I seem to remember cars in the 70s, 80s and 90s dipsticks always seemed to be spot on with a complete oil change. between oil changes you could actually tell if you needed to add a half quart or full quart. What the hell happened. Why is it so difficult now.

The dipstick in my 19 hemi is a joke. It's just a little section of somewhat flat metal on the flex cable. I just make sure that there's oil on the flat area and don't stress over it.

· My Reality Check Bounced
20,079 Posts
Not everyone, most of us used the manufactures fill specification, which is std practice on all pro shops I am aware of, Then made note of where the line was on the dip stick and moved on. In fact, when I worked as a gofer in a 1970s diesel shop thats what they did. Amateurs may have a different idea, some of which are quite vocal.

Diesels typically have a need more oil capacity mostly for turbo cooling. But you guys should know that.

Its not that big a deal, but with thinner oil that wicks up dip sticks, one has to use a different technique to get reliable results, its all in the wrist.... :)
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