Dip stick Accuracy, Caution

The Haynes repair manual states that the amount between the full and the low part of the dipstick is 1 quart... Well... I guess you might be right if the part of the engine interior gets wider and can hold more oil then the lower part of the engine.

 

Thanks for the info. I estimate that Prius needs ~3.75 qt to reach the full mark. Do you agree with that; and if so, does this mean that your dealer's mechanic had added ~4.4 qt when doing the refill?

 

I checked the oil on mine at about 100 miles and it showed 1/16" above the full mark on a brand new car :faint:.
I have almost 1000 miles now and the oil dipstick shows even higher than it did the first time I checked it.
Whats up with that?

 

Its pretty normal for a new Prius to show an oil level slightly above the full mark. However, if your car was parked in the same spot when you checked the oil level both times, and the level is higher now, this might mean you have water condensation in the oil. An accumulation of condensation may happen if you don't drive the car on the freeway, enabling the engine oil to get hot enough to vaporize its water content. I suggest that if this concerns you, try taking a long drive.

Patrick Wong

 

I always check it in the same spot in my garage and when it is cool.

Where I live ALL drives are at least 50 miles round trip. My last drive was 211 miles.
The oil looks clean and not milky at all. I would have to assume that since the factory put oil in it (or is it dealer prep), that maybe the dipstick is possibly off a bit.

 

The factory supposedly puts in 0w20 oil when they build the car.

 

I've heard that was a recent production change as well - but has anyone seen proof that this change was made: such as an owner's manual change, revised oil cap markings, or a TSB?

This is a mystery - if the oil level increases, I can only think of the following reasons:

1. Water condensation (that you've ruled out)
2. Engine coolant leaking through the cylinder head gasket (not likely if the oil appears normal in appearance)
3. Variability in the way that you are reading the oil dipstick (you said that you wait for the engine to cool down, so that should not be a big factor)
4. Someone added a tiny amount of oil to mess with your mind

 

No one else here to add any oil.
Maybe the first time I checked it, the dipstick hadn't been seated all the way by service for a pre buy inspection? But that doesn't make sense either because I usually pull the dipstick and wipe it and then recheck.
Right now the oil is about an 1/8" + above the full mark.
Maybe the stopper has slipped a little when I put the dipstick back in?

 

Many here prefer to use 3.5 quarts, which puts the level between the dipstick marks. If your reading is 1/8" over full, you can pull a quart of oil out and still be safe.

 

Got my Prius back from a service and the oil was exactly on the top line. Pretty impressive. I think they use a computerized oil dispenser that gives the exact amount needed for that model car.

This is a pretty big dealership who specializes in Lexus really.

 

Maybe I should take it back to the dealer and ask why it is overfull?
I guess that another possibility is that there is a slope to my garage floor.
What happens if I leave it "as is"?

 

If your car is new, the factory filled the engine oil that way. Other new Prius owners also reported that their oil level is a bit above full. Nothing will happen, if you leave it as-is.

If the oil level bugs you, just drain out 1/4 quart, and call it a day.

 

As long as it won't hurt anything, I'll just leave it alone.

 

I've seen lots of folks report a drop in FE upon filling to the top mark or above, so I accept it's true - but for the life of me, I can't figure out why.

The mass is negligible; eat a heavy meal and the driver's mass goes up more than the weight of a quart of oil.

I think I once read someone speculating that sloshing could be a factor, but again, 1 quart of oil sloshing seems negligible compared to the fuel tank.

Can anyone enlighten me? Why do you think overfilling has a significant effect on FE?

(Again: not questioning it happens, just perplexed as to why it happens.)

 

The theory is that the crankshaft is splashing against the crankcase oil level when it is too high, thus causing additional friction.

I used to routinely fill with 4 qts since the spec is 3.9. After reading all the concern about this, I now fill with 3.5 qts. Can't say that there's any mpg difference, but I feel good saving 0.5 qt of oil per change!

I suppose if your crankcase was filled with 4.5 or 5 qts, you might be able to discern an mpg decrease.

 

It's a bit confusing to me as to WHY the factory would overfill the crankcase if, as has been posted, it can possibly cause problems with the FE or the motor itself?
Patrick Wong said

Patrick Wong said

bat4255 said

 

The amount of factory overfill is probably 0.25 qt, not enough to cause problems.