It's the oil level, Holmes!

[Philmo]

Amazing, but I wish I knew why...

After taking our 2007 in for a free "Spring Service Review" and demanding that the oil -- at least 3/8" above the full dimple on the stick, from a sister dealerships recent oil change -- be drained to normal levels we were still averaging only 47 mpg whereas last year at this time we saw 54.

The next couple of tanks showed no improvement and I was starting to suspect new tires. Desperate, I considered asking a neighbor if we could switch tires for a week. He has a well-worn set of original Goodyears.

Then I checked the oil level again, cold, and it was just slightly above the full dimple. So I drained it down to halfway between the two dimples -- still within operating levels according to the manual.

The result? We're back into the mid 50s. Which begs two questions:

1) Why isn't my local Toyota dealer aware of this issue and instructing their techs to avoid over-filling on oil changes?

2) What exactly is happening where the oil overfill affects mileage?

Thanks...

[john1701a]

Here's an interesting insight to the oil-overfill problem, something that hadn't even crossed my mind until a friend recently clued me in...

Prius is made in Japan. The engineers there used measures most convenient to them: metric. For example, the "sweet spot" for highway cruising with the Classic model was 62.1 MPH. That just happens to be the maximum speed for electric-only driving too. It's a rather odd value, until you consider metric. That's because it is precisely 100 km/h.

You know what else is a precise quantity? It's the oil level. We (as owners in the US) determined the ideal to be about a quarter-inch below the "full" mark. That's a clusmy amount when dealing with quarts; however, it is not for the metric equivalent: 3.5 liters.

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[hiremichaelreid]

Originally Posted by john1701a

For example, the "sweet spot" for highway cruising with the Classic model was 62.1 MPH. That just happens to be the maximum speed for electric-only driving too. It's a rather odd value, until you consider metric. That's because it is precisely 100 km/h.

You know what else is a precise quantity? It's the oil level. We (as owners in the US) determined the ideal to be about a quarter-inch below the "full" mark. That's a clusmy amount when dealing with quarts; however, it is not for the metric equivalent: 3.5 liters.

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Cool !

Good to know here in metric Canada. Too bad Mobil 1 comes in 4.4L jugs here. I'll just have to do 5 changes with 4 jugs...

So is the max coasting speed with ICE stationary 42 MPH or 67-68 KMH ? I wonder if the ECUs work in metric and convert to Imperial when needed/requested. Do US Prii have MPH/KMH switches like here ?


I've had my Prius 1 week now. Bridgestones at 50/48 with 1400 KM on them and the car. Managed to eek out 4.1L/100KM on my 32 KM commute tonight; a new low. Now I need to lower the oil.

What's the easiest way to lower the oil ? Can I suction it out through the dipstick with thin tubing ? Would a clean plastic tubing keep the oil good for used oil analysis ?

I imagine things will get messy if I try to remove the drain plug briefly or the oil filter...

[dogfriend]

Originally Posted by hiremichaelreid

What's the easiest way to lower the oil ? Can I suction it out through the dipstick with thin tubing ? Would a clean plastic tubing keep the oil good for used oil analysis ?

I imagine things will get messy if I try to remove the drain plug briefly or the oil filter...

You can suck it out through the dipstick; I did this when the dealer overfilled my engine at the first oil change (I don't take it there anymore). Ideally, you would find a small diameter, relatively stiff piece of tubing. I was lucky to have a 3' piece that I found at work.

You could also remove the filter and drain it out and reinstall. Of course, this will be messier, but will work. I wouldn't try the drainplug.

[edthefox5]

[quote=john1701a;635367]Here's an interesting insight to the oil-overfill problem, something that hadn't even crossed my mind until a friend recently clued me in...

Prius is made in Japan. The engineers there used measures most convenient to them: metric. For example, the "sweet spot" for highway cruising with the Classic model was 62.1 MPH. That just happens to be the maximum speed for electric-only driving too. It's a rather odd value, until you consider metric. That's because it is precisely 100 km/h.

You know what else is a precise quantity? It's the oil level. We (as owners in the US) determined the ideal to be about a quarter-inch below the "full" mark. That's a clusmy amount when dealing with quarts; however, it is not for the metric equivalent: 3.5 liters.

No. 3.5 quarts with a dry filter brings it exactly to the mark as I have seen posted on this site oh maybe 500 times and personally experienced 3 times so far.There's 1.057 quarts in a liter. 3.5 liters of oil would put you well over the mark enough to make you run back to the dealer and demand satisfaction as so many posters I see here do.

[dogfriend]

Actually, I measure the amount out with a graduated container - 3.7 qts puts the level just below the mark for my car. 3.7 qts = 3.5 litres

However the Toyota manual lists the refill capacity with filter change as 3.7 litres or 3.9 qts. Which is clearly too much. Go figure.

[hiremichaelreid]

Originally Posted by dogfriend

Actually, I measure the amount out with a graduated container - 3.7 qts puts the level just below the mark for my car. 3.7 qts = 3.5 litres

However the Toyota manual lists the refill capacity with filter change as 3.7 litres or 3.9 qts. Which is clearly too much. Go figure.

I think "too much" in Toyota's eyes is over the high mark on dipstick.

Perhaps the issue is the amount of old oil left over after a drain ?

[chrisspaulding]

Originally Posted by dogfriend

You can suck it out through the dipstick; I did this when the dealer overfilled my engine at the first oil change (I don't take it there anymore). Ideally, you would find a small diameter, relatively stiff piece of tubing. I was lucky to have a 3' piece that I found at work.

You could also remove the filter and drain it out and reinstall. Of course, this will be messier, but will work. I wouldn't try the drainplug.

I can't get over 46mpg. Maybe too much oil is why!!
I'm leaving myself open for a good joke here, but how would one "suck it out through the dipstick" with tubing? You mean manually?
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[Speedwing]

Get a cheap Harbor Freight vacuum pump for bleeding brakes and you can use it for getting the oil out through the dipstick. You just need some longer tubing which can be bought at a store that sells fish tank supplies, even Walmart has it. We have some pool water shooters that would also work as vacuum pumps with added tubing.

[dogfriend]

Originally Posted by chrisspaulding

but how would one "suck it out through the dipstick" with tubing? You mean manually?
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^^^ What he said. You use a hand operated vacuum pump and a brake bleeder which is just a small container with two openings in the lid.

If you try to suck it out "manually", please take video and share it here.