Oil Change Interval

Don't make more into the process than what it is. Just follow the owners manual with regards to mileage and how much oil to use. There is no magical number, like 3000 miles changes that came from the 60's. Those days are long gone, engines and oils are much better.

 

If your car were under the original warranty, I'd say every 5000 miles. You can do what you want, however. Unless you are driving on sand in the desert, you shouldn't need to change your oil at LESS than 5000 miles or 6 months. The Prius is gentle on oil. If you run synthetic oil, such as Mobil 1, you could probably go 10K-12K miles on a change, or once a year. With conventional dino oil, maybe 7500 miles/8 months. If you are really interested, check out Bob Is The Oil Guy and do some used oil analysis.

 

Toyota recommends every 7,500 miles. I do too, since I owned one and changed the oil on it.

Also, you'll find this helpful... Classic Prius USER-GUIDE

 

<div class='quotetop'>QUOTE(nitewolfgtr @ Apr 24 2007, 10:24 PM) [snapback]429580[/snapback]</div>

Buy one then!

 

I would consider running one or more UOAs (used oil analysis) on the car, with the oil you choose to use before deciding what OCI to stay with. According to the guy who interprets my results, there are a fair number of Prii which show rather substantial fuel dilution of their oil. If such dilution reaches a critical point, it can be a serious problem. My car has shown heavy dilution on one UOA, so I'm watching it carefully. Mine is an 04 that I bought Toyota Cert Used so I've also got a 100k drivetrain wty to preserve. Toyota's recom for the second gen car is 5k miles, so I'm going no further than that for now.

Here is a link to a thread discussing that UOA: Click here.

 

<div class='quotetop'>QUOTE(ekpolk @ Apr 25 2007, 03:01 PM) [snapback]430001[/snapback]</div>

I'm wondering if a handful of Prius cars have this issue, just like a handful of Toyota's had the sludge issue. I've never had fuel dilution based on my UOA.

I'm sure the EU market Prius - with their 12 month or 10,000 mile interval - would have had issues by now if fuel dilution is widespread.

 

<div class='quotetop'>QUOTE(jayman @ Apr 26 2007, 05:47 AM) [snapback]430397[/snapback]</div>

As you may or may not recall, my first analysis indicated fuel dilution. For some reason or other, I haven't gotten the second analysis back. It was sent in nearly 4 weeks ago. I'll have to give them a call to see if they didn't get it. Either that, or the report got lost in the mail, or my wife put away (she doesn't toss it) the mail before I got to see it.

Dave M.

 

<div class='quotetop'>QUOTE(jayman @ Apr 26 2007, 07:47 AM) [snapback]430397[/snapback]</div>

I suspect it may be either one deviation or defect that appears in only some Prii, or it's a combination of factors that if they appear together in ANY Prius, result in excessive fuel in the oil. Now what those factors might be, I don't know -- it's just my current theory. I will be watching my future UOA to see if it's a consistent thing. Also, it could well be happening in Euro Prii, just without ill effects. We have several cases here (and at BITOG as well) of owners successfully using xw-20 oils in their cars. This being the case, I'd not really expect problems, at least wear related ones, until the dilution got really outrageously high. I had 1.78% dilution in Penz Plat syn 5w-30, and it had just dipped into the upper end of the 20 wt range. My wear numbers were pretty stellar anyway. I very probably could have run this oil out to 10k miles with progressively increasing dilution, with no ill effects. That said, all this begs the question of there the trouble threshold lies for a Prius that's dumping fuel into its oil. More homework to be done. . .

 

<div class='quotetop'>QUOTE(ekpolk @ Apr 26 2007, 02:27 PM) [snapback]430776[/snapback]</div>

A related question is "If we have above average fuel dilution, if the problem (whatever it may be) were corrected, would we be getting a noticeable improvement in mileage. I suppose it wouldn't take a lot of fuel lost into the oil to cause dilution.

Who's an expert on this?

Dave M.

 

When I sent my first oil sample to Blackstone and found high %fuel, I presumed 'rookie error' sampling technique. But in light of the fact that Prius often has trouble getting up to radiator-thermostat-opening temperature, there may be more to it than that.

I've an oil sample in the mail to them now, and will know a bit more, soon.

 

<div class='quotetop'>QUOTE(dmckinstry @ Apr 26 2007, 06:46 PM) [snapback]430817[/snapback]</div>

Actually, when an oil is sheared down, you - temporarily - have an improvement in fuel economy. A dirty little secret of the API "Starburst" oils that are rated for Energy Conservation, is that they do quickly shear. The polymers don't recover and the oil then begins a process of rapid thickening, hence the API "pass" rating if their wonderful oil "only" thickens 250% in the test.

So I would not expect any change in fuel economy

I much prefer a somewhat lower viscosity that is also stable, hence a synthetic 0W-20 or a well refined 5W-20. If I pay money for and pour in a 0W-20 or a 0W-30, that is what I expect to get out at the end of the interval. Within + or - 5%, that's reasonable.

Fuel dilution in excess can cause rapid lobe wear on conventional camshafts with pushrods. There can also be problems with main bearing wear, and even losing the crosshatch pattern on the cylinders. This usually needs a consistent 5-10% fuel dilution over long periods of time, so it's best to resolve any leaky injector problem ASAP

<div class='quotetop'>QUOTE(ekpolk @ Apr 26 2007, 05:27 PM) [snapback]430776[/snapback]</div>

WHich is why a routine used oil analysis is so important, as that is the only way to answer your question. Short of tearing down the block after every oil change and making careful measurements ...

 

If you change your own oil, how will Toyota know if you did every 5k during warranty period? Do we need to keep receipts for the oil/filters?