Water In Oil?

[Oggi]

Hi Guys,

I've just done my first Prius oil change this morning, a couple of things I've noticed worried me, maybe someone could put my mind at rest.....

First thing was that I did find a cerain amount of creamy white sludge inside the oil filler cap and hole, I'm hoping it's just that our vehicle rarely does journeys longer than about 3 miles so is not attaining sufficient engine temperature to burn off any H2O that finds it's way inside the engine and not a head gasket issue, if anyone has had a similar experince it would be reassuring to know, any comments & speculation over probable causes are welcome.

Secondly I noticed that with the filler cap removed and engine running the is a lot of air movement in the filler hole area, again I'm hoping that someone will confirm that this is to do with the way the emission system works or something, it's just that when I was much younger working on much more basic engines air movement like that in the filler cap hole meant problems.......

Other than that the car is fine, no leaks, no loss of fluids etc, previous oil change was 12 months and 3k miles ago by a dealer.

NHW20 model (2004) with 42k on the clock.

Thanks & Regards to you all.

[Chris Dance]

The creamy "sludge" could come from emulsifiers in the oil. I have had this on other cars but not on the Prius so far.

I have never run an engine with the oil filler cap off so I cannot help you. Why would you want to do that?

If there was water in your oil your sump level would increase and when you drained the oil you see water globules in the drained oil.

Maybe a daft thing to say but please ensure you are using only the oil recommended for the Prius engine. The oil viscosity is very important to satisfactory engine performance.

If you are worried go to your dealer or drain a sample of oil and send it to the oil manufacturer for analysis. I sent a sample many years ago to Castrol and they were very helpful.

[Oggi]

Hi Chris,

Thanks for the reply, I'm using Mobil 1 5W-30 which I believe is correct for the Prius, I cannot vouch for whatever the dealer put in before..... The filler cap was only removed for the obvious reason (filling!) it's just that I ran the engine for 15 seconds or so to ensure that the new oil filter had been filled correctly and to get a correct dipstick reading (1/4 inch below full mark) it was then that I noticed the "heavy breathing" through the open hole. I know many years ago that some if not all filler caps had a sort of wire wool filter in them that allowed a certain amount of crankcase pressure to breathe through the cap, I suspect though that in these days of emission awareness that that is no longer the case as the Prius cap is fully sealed.

I have checked all fluid levels in the vehicle and they are correct so it would be unlikely that there could be enough unwelcome fluid in the engine oil to substantially alter the oil level reading on the dipstick and there was nothing untoward with the drained oil that I could see.

Forgive me but I just have such little faith in the dealers, I cannot remember ever speaking to one that actually seemed to know what they were talking about, and some of the practices I have actually witnessed over the years of driving company vehicles have been, well, worrying is putting it politley.

My vehicle is well out of warranty and the last thing I need is to have work done without good reason, although for specific specialist jobs (brake fluid replacement for one) I understand they are the only choice.

Hopefully as you suggest, the previous oil was of less than top quality..

Regards, Mark.

[Chris Dance]

Hi Mark,

What a shame your experience with dealers is so bad. Were they TOYOTA dealers? I have also had terrible dealings with dealers over bad work but never Toyota dealers.

From what you have said I do not think you have a problem.

Try this: Clean the emulsified "sludge" off the filler cap. Go on longish journey using the motorway if possible. Check the filler cup on your return and whilst the engine is still hot. As you well know using a car for very short runs all the time is not so good.

Trusting all will be well.

Chris.

[hedleyf]

:D

Hi,

I would not worry to much about this as I have seen it on several occasions , I think the attkinson type valve arrangement and its limited rev range have something to do with it, it basicaly opperates as a stationary engine and when you think about it its not running all of the time so condensation builds up , they do pump quite a lot from the filler cap this is mainly because of a shortage of lower piston compression space and flutuations with lower end pumping and crank movement, this is why its very important not to overfill with engine oil as this then reduces sump air space, 5/30 is correct but I d'ont think Mobil 5/30 is classed as a fuel saving oil for max MPG but the benifit is that it is higher than some oils in phosphous which is a good thing if you have a timing chain as in the Pruis. The breather on the oil filler went years ago as its now illegal to vent this of to the atmosphere it is normally returned to the induction where it is burnt off. Hope this helps '

Hedley.