Oil Change Interval

Hi John, synthetic oil has always tested well in Prius for up to 10k miles, by which time its total base number is starting to get low. We have seen *very* little evidence of wear metals accumulating in the oil. I used to change my oil filter at the 'midpoint' but am now letting one filter go the whole way.

I am also a fan of engine oil analyses, which are really the only way of knowing what is in there. It could be argued that those are particularly important for extended oil intervals, but in fact everybody would be better off knowing what's going on inside. At the same time, in Prius, oil analyses usually are very boring. Whether the engine is simply very accurately machined, or if the 'hybrid lifestyle' really reduces wear during startups, 'lugging', and fuel enrichment during 'high load operation', we really don't know.

For extended oil change intervals, the possibility of accumulating ingesting dirt in the engine (which can cause abrasive wear) is obviously increased, so it becomes even more important to confirm that the engine air filter is maintained in good condition.

There are other threads here about 'bypass oil filters' which if I understand them correctly, may allow the Prius to go even longer on one batch of oil. Essentially out to the oil's true lifespan, whatever that might be. That modification will be of interest to some Prius drivers.

 

<div class='quotetop'>QUOTE(john1701a @ Sep 6 2006, 02:45 PM) [snapback]315427[/snapback]</div>

Currently I'm going with 5,000 on synthetic.

 

for those of you in cold climates in the winter time I think if your an average driver who does 2 15 mile trips per day, to work and back, and the OAT is at or about freezing I think a change in the late fall and again in late spring is probably all that's really needed. 10,000 on a synthetic is probably about as far as I would want to go but a UOA will tell for sure. I just did a holiday trip and in 3000km the ICE only operated 68% of the time, and this was gone over in the thread that I started on it. As far as I'm concerened that works out to 2000 and change Kms I just looked at the oil and it's clean as when I put it in 4 day's before the trip. I'll change it again in the spring unless some extenuating circumstances occure in the meantime.

 

In The Netherlands, Toyota recommends oil change every 15,000 km.

 

<div class='quotetop'>QUOTE(john1701a @ Sep 6 2006, 04:45 PM) [snapback]315427[/snapback]</div>

You can only get a legitimate answer to your question by doing a Used Oil Analysis, like I have. Overall, with Mobil 1 and the Toyota filter, putting almost 7,000 miles on Mobil 1 0W-20 over winter short trips, was nothing. Clearly, at least with Mobil 1, the oil is good for much more.

I would suggest the EU oil change interval of 12 months or 15,000-16,000km should work ok if you use Mobil 1.

Once you have over 6,000 miles on the oil, a sample every 1,500-2,000 miles would be helpful to establish baselines. The sample is usually less than 80ml, so you're not removing a huge amount of oil. What you want to track are wear metals, TBN, insolubles, etc.

<div class='quotetop'>QUOTE(Sho-Bud @ Sep 9 2006, 01:02 PM) [snapback]317017[/snapback]</div>

Believe it or not, here in North America, especially the U.S., there are many folks who believe if they run over 5,000km on the oil, the car will self-destruct

 

I would be very interested in some of the oil wear results.

I definitely agree that the Prius should be able to handle longer wear than most cars especially when you feed it mobil 1 syn

John, btw, just used your oil change guide for my first oil change on my '06, thanks alot for putting that together. Was a piece of cake with your guide

 

Where does one go to get used oil analyzed?

 

<div class='quotetop'>QUOTE(MechaJohn @ Sep 15 2006, 12:16 PM) [snapback]320125[/snapback]</div>

http://www.blackstone-labs.com/ is one of the sources.

I was talking to my co-worker today about the car. He recently purchased an Acura TL. He told me that his oil change interval is 7500 miles with synthetic blend oil. I can't imagine that our car needs to change oil shorter than his car since our ICE is not running all the time. I will definitely change to 10k intervals after the warranty is up. And will do a used oil analysis just to be sure.

 

I did a used oil analysis on my last oil change. The info was 5w30 for 10,300 miles. mostly hot summer conditions and about 2000 miles per month. I used ANA laboratories for the analysis. Cost was 25$. The results were:

Severity code 1 (lowest rating) meaning that I could have continued to use the oil. (note said "overall satisfactory conditions")

Wear metals in ppm by weight showed:
Titanium <1
silver<1
copper 2
lead 1 tin <1
aluminum 5
nickel 1
iron 28
chromium <1
Cd <1
sodium 9
boron 108
silicon 23
water <.05
%soot <0.2
glycol N
fuel <0.5

VIS. @ 100 C. Cst 10.18

additives:
molybdenum 144
magnesium 31
calcium 1960
barium <1
phosphorus 496
zinc 919

I have decided that 10,000 miles is totally acceptable for our two Prius. We use 3 quarts only per oil change and experienced no detectable reduction in oil level after 10,000 miles. I've been anxious to share this info with all of you.

 

<div class='quotetop'>QUOTE(efusco @ Oct 7 2006, 08:31 PM) [snapback]329640[/snapback]</div>

You might as well skip the 60k oil change as your drivetrain warranty will have expired anyway.

 

I change mine every 12,000 (lots of city driving) to 15,000 miles (if heavy on highway; road trips).

I do use Redline or Royal Purple full synthethic 5w30 with Mobil1 or K&N filters so the oil does hold up quite well. Even at 15,000 miles the oil does not look as dark as you would imagine. Now i do agree that the interval might vary depending on your driving habits, conditions, and what not but 5,000 is a joke!

Most people on the forums will probably recommend you something along 7,500 - 10,000 miles which I find perfectly reasonable if you are using full synthetic oils. 7,500 miles for regular or synthetic blend (<--waste of money).

 

<div class='quotetop'>QUOTE(john1701a @ Sep 15 2006, 11:15 PM) [snapback]320390[/snapback]</div>

Excellent point. This is one key advantage of synthetic and heavier weight oils in particular that's less valuable here.

On the other hand some heat is vital to burn off corrosive, acidic combustion byproducts that end up in the oil. In a car that is rarely driven long enough to fully warm up the oil, more frequent oil changes and/or oil with a higher TBN (total base number) can be important to protect the engine from internal corrosion. Again, this is really only a concern for cars in cold climates that are primarily drawn short distances. Of course, there are reports of Priuses taking as much as 10 miles to fully warm up in very cold climates.

 

Thanks for posting the UOA Ray, sorry to not have noticed it earlier. Please also say what the ending odometer was on this oil and the brand/type that you are using. There have been a few other recent UOA's posted and it is probably time to put them all together.

 

A book in the 1970's titled "Drive it Forever" when into exhausting detail of why regular oil changes is good for your engine:

- Oil viscosity deteriorates. In other words, 0W-20 won't stay that way.
- Acid builds up in oil and eats on the engine
- Accumulated sludge. Oil will mix with water under the engine pressures.
- Dirt gets in the oil, even with good filters.

 

<div class='quotetop'>QUOTE(john1701a @ Sep 6 2006, 08:49 AM) [snapback]315186[/snapback]</div>

This is a very late reply to an ongoing discussion, but I'm putting it in today as I just asked the service department if letting the oil change interval go over 5000 miles would affect my warranty. I was told that even letting it go up to 6000 miles wouldn't affect the warranty, but not to push it much beyond that. I'd been going to great effort to be certain the interval was always less than 5000 miles, but won't worry about the slight overage anymore. I'm coming up on my 35K miles oil change, but only have 34100 miles on it now. This is with normal oil and not synthetic.

In spite of this, every time I get an oil change they put on a sticker showing the next oil change in 3 months or 3000 miles.


I'm reasonably certain that (even if the warranty would lose its effectiveness), going 7500 miles wouldn't be harming the engine under normal clean driving conditions. I'm not talking about a lot of dusty or gravel roads though. Probably a lot longer interval with synthetic. When I get up to 60k miles, I'll probably start doing my own oil changes and use synthetic as well.

Dave M.