Oil consumption info

Well, just keep checking the oil frequently and count your blessings . . .

 

Keep checking the oil.

 

Its imperative you let the car sit overnight before checking the dipstick if your checking for any oil loss. The VVT vane in the cyl head is oil driven so it holds alot of oil and that takes a long time to drain back to the pan. It holds about 3/4's of a quart I would say.

If you just pull over and check the oil it will show lower than it really is. Alot lower.

I check all my cars oil every Sat morning before they are started.. My G2 had a very minor oil loss also and moving up to a 40 weight oil fixed mine too without any mpg hit.

The car was probably raised on dino oil so after that good run you just did I would change it again with synthetic it may help loosen up the rings.

 

What engine flush product?

 

I know lots of people who don't drive on long trips and just Prius around their city and they often go a year a or longer without an oil change... I'm sure we all agree that's not very smart. I suspect if you use the the cheapest oil possible and it's more than a year between changes, the oil loss in an old engine is going to be much higher.

I'm also working on a still yet un-proven theory that once a Prius engine gets a quart low, it starts burning that next quart of oil at a much greater rate. Wondering if others can confirm this?

 

My experience is that my Gen2 uses/burns more oil when driving over 65mph, over mountainous terrain and when the crankcase is completely full (top dipstick dot versus halfway in-between the full and low dots on the dipstick). The engine is specified as using 3.5L of oil (with new oil filter), which according to the manual is equivalent to 3.9 quarts. I usually refill with 3.5 to 3.6 quarts of motor oil at oil change (thereby getting oil level to my desired level: halfway in-between the full and low dots on the dipstick).

PS I have an oil change coming up shortly. At that time, I am going to try 3.6 quarts of straight 40W oil. I will report back the results. Additionally, I will be installing a magnetic drain plug from ebay (with stock threading of M12x1.25). The hope is that I will be able to remove steel and cast iron waste already in the oil pan at subsequent oil changes (and prevent such waste from traveling through the oil system).

Emptied my oil catch can yesterday. I emptied the catch can before the car was started for the day. I found a strong gasoline odor and also an ice ball about a size a little larger than a golfball. Seems like this catch can is really preventing gunk from getting back into the engine and ultimately the catalytic converter.

 

I'm confused? Your profile says you're driving a Gen2 Prius not a Gen3, yet oil catch cans can't be installed on a Gen2?

 

I have a 2006 Gen2 with an oil catch can connected to the PCV valve (source of blow-by, moisture and crankcase fumes) which is attached to the catch can. In turn, the other port on the catch can is attached to the inlet near the throttle body (where the PCV hose originally attached). I used the following catch can from ebay: New Silver Aluminum Baffled Oil Catch Can Tank Reservoir Breather +Fittings J6I4 | eBay

PS Clear hose provided with kit is not the greatest. I am planning to upgrade to oil/gas resistant hose in the near future.

 

2007 Touring


iPhone ?

 

I disagree. keep oil at the full line. I bought my 07 new and have always without exception kept it at the full line and my car at 150,000+ miles eats no oil at all. Its a tiny engine it needs all the oil it can get.

I believe the main reason these engines eat oil is the top oil ring on the piston is damaged. Very easy to damge it just run it low on oil that ring will go first. Its a tiny motor it needs all the oil it can get.
Oh and using the worlds worst oil at the dealership does not help either.

 

Context please. I don't remember using those words (namely, "worlds worst oil at the dealership") in this thread or any other thread. Please provide source for these words.

 

As far as I can tell, the Toy 1.5l engine found in the Gen2 Prii does NOT have a windage* tray. Which means that the crankshaft is contacting the oil in the pan for a NON-lubricating purpose creating power loss and lots of oil mist which eventually runs through the PCV system. My POV is that by keeping the oil level halfway in-between the full and low dots on the dipstick, this technique reduces oil windage. And, thereby reduces oil mist that needs to be handled by the PCV system (which in turn reduces oil consumption). Just my POV (I don't have any hard studies on this this issue for the Toy 1.5l engine).

*- "windage" is defined as the power loss caused by the friction of the oil in the engine coming into non-lubrication contact with the moving parts inside the engine. For the most part, this is oil splashing against the counterweights of the crank as it spins.

PS remember crank and rods are oiled via oil pressure through passages in the crankshaft. With regard to the cylinder wall and pistons, oil is squeezed past the rod bearing and is then slung onto the cylinder wall where it lubricates the piston rings (and cylinder wall).

PPS "tiny engine it needs all the oil it can get." implies that the fuller the crankcase is the better. IMHO, as long as there is enough oil for the oil pump to have a continuous supply of oil then you have enough oil.

Link to Amazon Windage Tray for Toyota 3TC engine:

Link provided to show what a windage tray looks like, 3TC engine apparently was a Toy 1.8l peformance motor from the 80s.

 

Only on this site will someone argue with you about keeping the oil at the full line.

Very very little gunk from the pcv into the throttle body. Looked at that many times.

Here's what 13 years and 150,000 miles keeping the oil at the full line looks like.
Virtually no wear whatsoever on the cam journals. I expect the bottom end looks the same.

 

Take a look at this thread (where many PC posters agree that filling to the fill mark is NOT always best): Too much oil? | PriusChat

I am not trying to piss you off. But the dipstick has a range for a reason: i.) lower dot means add oil; and ii.) upper dot means full. IMHO, to assume the full dot is the "best" position/level for oil is without susbstance. Please provide support for your position: the full dot is the "best" position/level for oil level.

PS You have not addressed the windage issue.

PPS My Gen2 has not had as kind a life as your Gen2 (prior owners of my Gen2 changed oil but not as often as I would have changed it). Thus, what works for you many not work for me (because we have different facts at one level based on frequency of prior oil changes for the two vehicles).

 

Great discussion... I'm learning lots...

Always wondered the specifics of what reduced MPG if you added too much oil. It makes sense that there's more friction in the crankshaft due to counterweights smacking into all the extra oil.

But I also suspect that Toyota did design Prius crankshaft lubrication to be done with not just the oil pump, but by a light splashing of counterweights in the oil reservoir because when you get 2 quarts low on oil the first warning codes are usually engine misfire codes. And according to a thread on Prius chat, those initial misfires are actually from excessive crankshaft vibrations due to a lack of lubrication.

So that means that even though the oil pump still has enough oil in the oil pan to pump into the crankshaft, the crankshaft is not getting enough oil, because there isn't any additional splash...

The only question I'm still trying to figure out is does a Prius burn oil way faster once it gets more than a quart low on oil?

 

What you get from windage is oil whipped up into a mist, which passes via the PCV into the intake manifold, where it pools below the throttle body. The Gen 1 Prius could throw a no-start code if it got too much oil accumulated in the intake -- there are numerous threads on the Gen 1 forum on that subject. That's where I picked up the practice of keeping the oil level below the full mark. The Gen 2 seems to have overcome that starting problem, but I still see oil in the intake of my wife's Gen2.

Oil level below full could be a problem if you took curves like Mikka Hakkinen -- in that case the transverse Gs you'd be subjecting the car to could push the oil to one side of the sump and expose the oil pump intake. That would starve the engine of lubrication. But most people don't drive their Prius like that. Our Touring has 130,000 miles, uses no oil, and in the 95,000 miles we've owned it I have never filled the crankcase to the full mark.

 

Can’t tell for sure, but I thought you are using (Group VI aka PAO) Redline oil. That would definitely have something to do with these pictures.

I personally like the oil between the markings, in particular since I’m not always checking the oil level while the Prius is on a level surface, meaning the level could be skewed to be full but actually overfull.