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If you're never changing your oil, that also means you're never changing your filter. The filter also gets dirty and clogged. Why cheapen out on the most important maintenance a vehicle needs.

 

Yup. And in Oz a full range of oil grades are shown in owners manual. Funny.

 

That's a faulty analogy, because, as you said, salty water never leaks out of the ocean, unlike the contaminated oil that leaks from an oil-burning engine---gradually taking contaminants with it, including any suspended metal particles too small to be captured by the filter.

 

We are talking about a 3.5 quart fill, where you consume a quart and then have 2.5 quarts left and have a choice of top off, or change the oil. I am the cheapest person I know, but I don't see value in spending one quart of oil to keep 2.5 old used quarts in longer without draining it. You are assuming that the 2.5 quarts remaining is still pure oil, uncontaminated by coolant or water. I highly doubt that the quart that got consumed took with it its proportional share of wear metals and particulates, and I think it more likely that abrasive contaminates will be more concentrated the older your oil. If you read the amsoil propaganda there is considerable evidence that much wear is caused by particles small enough to go right through an oil filter (which is why I get oversized purolator pureone filters when they are on sale).

All that said, the only instances I could find after extensive googling where a prius engine died involved letting the engine oil level get low/dry. Therefore a strategy of regularly topping off, checking level frequently, and never changing the oil will probably still keep the engine functional better than not checking the level between changes but changing it at 5k on the dot, as the latter strategy will involve running low unbeknownst to the owner.

 

It does depend on if he is leaking oil, or burning oil.

 

The debate on oil change intervals will carry on as long as we have internal combustion engines.The fact remains that lubricants, engine materials, fuels, and design are always improving.
Many years ago oci was 1000 miles. This has gradually increased through 3000, 5000, 10,000, 15,000, and beyond. Many people find it difficult to change what they have always done. This is there perogotive.
In the US the gen2 has an oci of 5000 miles. There are many reports from the US of the Prius begining to burn oil at circa 100,000 miles.

In the UK the oci for the same car is, and always has been 10,000 miles. I have yet to hear from a UK member who's Prius is burning oil. I am not saying it does not happen here, but my own Prius now approaching 130,000 with 12 oil changes uses no measurable "on the dipstick" oil between 10,000 mile changes using 0w20 synthetic oil. I know of a number of other owners with similar, and higher milages getting the same results. Not all are using 0w20 some are using 0w30 or 5w30 synthetic.

The Prius engine derived from a standard normal car engine runs at only 60% of the maximum rpms of the original, and most other normal petrol engines. Further it does not run all the time the car is moving.
In general terms the stress on the engine goes up by the square of it,s rpm so the Prius engine has a comparatively easy life.

John

 

Of course, as long as it's SUPER duty Prolong.

 

But engine running less also means more startups and colder running engine. Those will increase the requirements of the oil and increase its dilution with water, fuel and deposits.

 

Some people will spend hours "Googling" and discussing/arguing ways to justify avoiding doing the single most important thing you can do to maintain the engine....yes even a Prius engine. In fact it's so simple a child can do it. Check your dip stick every time you fuel up, change your oil and oil filter every 5,000 miles and address any unusual changes to consumption right away. Do this and you will have no problems, don't and the problem is your fault.

 

I agree with the fact that the engine possibly runs cooler. This depends on the type of driving. On the motorway "freeway" the engine runs continuously, but with the engine greater efficiency turns more of that fuel into energy leaving less to dilute the oil. In the city the engine will start and stop, but when it is stopped no fuel is diluting the oil.
Unless there is some other problem like leaking injectors oil dilution by fuel is virtually a thing of the past. Looking into the oil fill point of my engine there is no signs of lacquer, and the oil still comes out almost clear compared to past vehicles I have had where the oil came out completely black.
With the Prius when the engine is turning often no fuel is being injected, and to all purposes the Prius does not tick over. A time when much ware takes place. The high speed start of the Prius engine also remove some of the possibility of fuel dilution against that of a slow cranking engine waiting for one cylinder to fire before having enough RPM to get it running on all cylinders.
There is possibly another reason why oci's are longer in the UK, and Europe. A gallon of good quality oil is a minimum £50+ and we cannot afford to throw away oil that is perfectly serviceable. This is more than the cost of a full tank of fuel at to days prices. We may have been in the same situation as the US if oil derived products were as cheap here as they are there.
The fact remains though our UK Prius engines seem to be lasting at least as well if not better than it's US counterpart.

John.

 

I did not mean that Prius engine is more demanding on engine than “regular” engine. Most of the time it’s less demanding just as you told. But it’s just that especially on city driving cold engine (oil) temperature doesn’t evaporate the condensation and small bit of fuel that gets past piston rings off the oil as easily as in the regular car.

 

May I ask how many miles your Prius has done, and the amount of oil "if any" it uses between oci's, and what though's intervals are?
I realize you climate on average will be somewhat colder than the UK. Just trying to get a handle on why in the US comparatively low mileage engines are using oil. Although I only have relatively few UK Pri to compare them with.

John

 

I think the quality of the oil that you are using is probably much better. £50 = USD74.

You are paying ~3x the price that I pay for oil. Usually Walmart's sale price for name-brand full synthetic oil is $23 for 5 US quarts. For the 2004 Prius, I use 0W-30 Mobil 1 oil. The normal price is $26 and if you pay attention and wait for a sale, the price drops down to $23.

In another post you had mentioned that your drained oil is light in color. I change oil at 7,500 mile intervals and would say the used synthetic oil is pretty dark.

 

My Prius has only done about 160tkm or 100t miles. Oil change interval here is 15tkm or 9,3t miles. I don’t need to add oil between oil changes but level does drop in the dipstick.

My thoughts on oil consumption:
On other (older) Toyota engines oil consumption is many times caused by piston rings and piston oil drain holes getting clocked up. Prius engine uses pretty lose piston rings so they could be clocked up somewhat easily. US worse quality oil, maybe overfilling the engine oil, and maybe even sometimes doing longer oil change interval will all aggravate this. Also US has more long downhills where Prius is engine braking where engine will be sucking oil through valve stem seal. And then maybe in US people are less likely to check oil level in dipstick or they even think that Prius has some warning for low oil level and let their oil level drop and then get engine wear which will make everything worse.

 

All my Prius cars burn oil, except for my 2015. So I would say there are more Prius cars that burn oil than ones that don't......just based on my averages

 

Thanks for the input Patrick. When I said £50 for a gallon that was a minimum price for quality branded oil. Some oils are around £80. We can buy cheap unheard of brands generally of the 20w50 grade that are recycled products from about £20 upwards. I would not use these in any vehicle I own.
The oil drained from my Prius is used in my lawn mower and chain saw
The 0w20 used in the Prius is almost impossible to see on the dipstick when new "virtually colorless" when drained it has a brown tint, but is still transparent.

John

 

This is the first time I've heard of someone thinking topping it off is similar (or equal) to changing! When you change, you get all the crud out... topping it off leaves it in the engine.

I'm at 160k miles and change my oil every 7500miles (Mobil1). The engine consumes 0 oil between changes. I'm not sure what prius you're dirving that consumes 1 quart every 4k miles. The last time I had a car like that was my VW that leaked all over my driveway.