mobile-1 15k good to 4k milles only

I've been using mobile-1 full synthetic 5-30W extended preformance oil in my gen II prius since it had 2300 miles on it... now is has 41,500 miles on it.

I notice valve/lifter/cam noise developing at 4 to 5000 miles on mobile synthetic extended oil, which tells me the oil is breaking down.

When I change oil the valve/lifter/cam noise goes away for another 4 to 5k miles...The mobile syn oil then breaks down and valve/cam/lifter noise creaps back...

I will probably stick with mobile-1 extended but will not let it wear beyond 5000 miles....

A search on the internet about mobile-1 synthetic says it is no longer is a group IV oil (true synthetic) but a group III lower cost to produce fake synthetic...

Here is an interesting link with oil analisys comparing many mobile-1 types against plain old pensoil dino oil.... shows dino oil to have less iron and lead wear...

http://forums.nasioc.com/forums/showthread.php?t=1265711

Dont let current mobile-1 stay in engine longer than 5000 miles and most of all dont go to dino oil either..

But keep a keen ear out for engine noise from inadaquite lubrication...

 

I can confirm that fuel is getting into the gen II oil pan..
I've been siphoning 2.5 ounces of oil every 2500 miles to keep oil level at the prefeered mark on dipstick (3/16 inch below full mark)..

Prius always runs great averaging 54 mpg...

The fuel in oil contributing to mobile-1 syn breakdown..

 

Very interesting developement here....

Yesterday I drove on the freeway for about 35 miles after which the cam/lifter/valve noise quited down and the prius drove just like it had an oil change!

My orignal post was about mobile syn oil break down..At 4k miles.....

After longer drive with engine operating continously (30 minute freeway drive) oil now seems like new!! engine even has more power jusl like getting an oill change and nice and quiet engine again!!!

All my previous driving was stop and go city driving under 40 mph with one hour duration (ready mode) with each startup. Half that hour the engine is actually off. 50/50 engine on/off.. all though the engine seems fully warmed up 166 degrees (scan gauge temp but winter months) the oil may have not been fully warmed up...lots of cold winter air on oil pan?

I think the diluted oil under my city driving has found a low resistance path to the prius oil pump. circulating only the diluted contaminated oil through the prius engine. Not mixing with the good oil until I had an extended engine run conditon on a 30 mile freeway drive which hadn't happened before..

I have been siphoning out accumulated oil out of the dip stick port as my prius seems to breed oil (fuel contaminated oil) keeping oil level at the sweet spot on diip stick...

If my oil level is still on the increase after what I have learneed.. I hope now to be siphoning off only the fuel contaminated oil that should be floating provide the engine sits (off) long enough????


My research shows fuel to be lighter than gasoline;

unleaded 6.216 pounds per gallon.
Premium 6.350 pounds per gallon.
Oil weighs 6.84 pounds per gallon

The weighs of gasoline was confirmed from two internet sites..
The weight of oil was only found on one web site....
So additional research may be needed.....

 

I've got about 100 freeway miles now on 4k mobile-1
and the prius has gained even more preformance and is quiet and running just like its had an oil change.

although the oil level is about 1/16 inch from full I will be siphoning off the excess 2/16 inch (aproximately 2 oz) which will be the first siphone with this current oil fill...
previous fills i've had to siphone two different times in 6500 miles (5oz total siphone) and oil was probably at near full mark when changed at 6800 miles.

Durring the current oil fill I've tried to keep air/heater blower on low (excluding warmup) durring daytime driving which keeps the dc/dc converter at 13.78 volts as opposeed to 13.21 daytime volts without blower on..(nightime voltage is always 13.75 volts).....

This is not a defect of the prius dc/dc converter thats the way all genII prius charging systems work.....Battery fully charged no load on system battery is trickle charged at 13.2 volts....any load on 13volt system dc/dc regulator switches to 13.8 double trickle mode....

I had hoped the higher voltage would provide more complete combustion of fuel in the engine....and the accumulation of excess oil seems half as much from the previous oil fill......I cannot say absolutely that
the additional ignition coil voltage is the reason but higher voltage should help....(theoretecly)..

Note gen III voltage cycles between 14.2 to 14.9 volts for reasons beyond be. But perhaps gen III has less fuel contamination???

Oh now for the real reason for this post.....
If anyone decides to try siphoning oil from prius engine...be advised this can be just an messy as your worst oil change.... I've been using aquarium air hose purchased at walmart and discarding after use...

The slightest bit of dirt injected into your prius engine will surely negate any positive efforts.....and pulling that last inch of tubing from dipstick port always flicks oil somewhere.....My fear hear is that comtaminated oil is probably high in acid content and may eat through cooling hoses, fan belt, aircondition hoses..and the likes......

Walmart also sells a turkey baster that looks like a giant hypodermic needle that I use it conjuction with aquarium air hose for oil siphoning... not a perfect combination but somewhat okl.....the seal from hypo to hose could be tighter (wish).

If your are insistant on doing any of this nonsense try and keep the oil flowing in one direction by crimping off hose to eliminate any back wash that could further contaminate engine oil..... although aquarium air hose is transparent and clean looking who knows what microscopic junk is inside the hose......
And when removing that last inch of hose from diphole keep hand and absorbint paper towell right against dipstick tube to prevent oil flicking somewhere...

That all I have to say about that (siphoning)..

But Mobil-1 synthetic oil is the best Imho....And I will be using it for a long long time....

 

Here is a follow up on my fuel contaminated mobil-1 5-30w extended oil at 4.2kmiles..

I siphoned off 8 oz of mobil-1 from the top layer of pan oil (fuel is supposed to float)..this dropped the oil level from the full mark to about 1/2 inch below full mark...

I then drove the prius (8oz low oil level) noteing a much quieter engine.
..
This 8oz removal was after prius sat for 7 hours..
and the removed oil did smell of gas but not bad but
noticeable...

The next day after prius sat for 8 hours I siphoned off 16 more oz of top surface mobil-1 oil... this second batch of siphoned oil smelled identical to the first siphoned batch...

I didn't really think this wouid work as well as it did with the prius setting for only 7-8 hours.. an idle prius for a day or two would nodought allow more fuel to float to top surface..for better removal...

After siphoning the second batch I added approx 22 oz of new mobil 5-30 extended oil from a single 32 oz bottle purchased at walmart for 7.80 and was shocked at the color of this new oil almost clear like water....
I stopped momentarly while pouring into funnel...(did someone sell me water instead of oil)).... I have never seen mobil-1 look clear like this...I previously always purchased 5 quart jugs at walmart where the mobil oil looks yellow...... could the single bottles be different quality justifing the higher price ???????

Anyway drove the car on freeway for about 75 miles...
Prius drives wonderfull .... engine nice and quiet.....

4.2 kmile mobil-1 oil seems like new and only a slight hint of gas smell on dip stick.....I'm hopeing new oil that I added will help float remaining fuel to top of pan after an extended inactive resting prius...I will siphone a little more and see if gas smell goes away completely (hopeing)..

OTHER DRIVING HABBITS OF MINE THAT PROBABLY CONTRIBUTE TO FUEL IN OIL ... i SET AT PARK WITH PRIUS IN READY MODE ABOUT 1/2 HOUR PER DAY AND ALL CITY DRIVING....

i BELIEVE MY INJECTORS ARE LEAKING SLIGHTLY WHILE AT THE PARK EVERYDAY AND AT TRAFFIC LIGHTS.........MY ACCUMULATION OF OIL (CONTAMINATION) STARTED AT AROUND 29000 MILES ON PRIUS ....WHILE MY DRIVING HABBITS HAVE NOT CHANGED SINCE OWNERSHIP....i BELIEVE THE INJECTORS ARE WEARING AND DON'T BELIEVE INJECTORS CAN HOLD BACK 60PSI FUEL FOREVER.....

I PLAN ON SIPHONING ABOUT 1.5-2.0 OZ FROM MY PRIUS EVERY 1000 MILES OR SO.(AND REPLENTISHING)...CAUSE i DONT WANT TO CHANGE MY DRIVING HABBITS.....AND i LOVE THE SOUND OF A QUIET PRIUS ENGINE......iT SOUNDS EXACTLY LIKE IT DID WHEN I BOUGHT IT......

 

I would like to clear something up here.
I have been siphoning top oil out of my prius several days in a row not because the oil is being diluted this fast,
but to get fuel accumulated over 4 thousand miles out of oil...
And I dont know how much still setting time without driving is nessary to get all fuel out of oil...

I dont think anything is wrong with my prius other than mine doesn't burn any oil making it obvious that oil is being contaminated by fuel.\
I broke in my prius engine very well so as not to burn oil...

Also my girlfriend has gen III prius with 10k miles now. and with 2k miles on recent oil change her oil smells exactly like my gen ii prius
with 2k miles of oil dilution with fuel..

So I am siphoning oil out of both prius's.....

I find two days of setting allows fuel to seperate nicely and float to top surface.....

 

Extra info on our prius's.

I have about 8500 miles on mobile 5-30 extended. Having siphoned out 2 quarts, 4 ounces at a time my oil looks brand new.
I started my first siphon at about 4000 miles when I noted valve train noise.

All my driving is city stop and go...After siphoning my first 4 ounces from girl friends gen III prius...We drove to pioche for the solar eclipse
and the long drive burned off all residual fuel contamination from here prius and her oil smelled perfect...

I believe all internal combustion owners should be siphoning fuel off there top oil... especially with todays thinner oil 0-20 etc.

If you drive long distances with continous engine running your probably ok not siphoning...

But to put your mind at rest siphon top oil into empty plastic water bottle then siphone bottom oil into another empty water bottle..
after parked for 24 hours and smell the difference.......Bottom oil smells only like oil ...