Darwantae951

Ok, so I did my first oil change since I bought the car. I had no previous knowlegde of what had been used before, no receipts said anything about weight/viscosity, nothing...So I just put in Mobil 1 15W-50 Full Synthetic, and she's sprung a leak! what do you guys suggest, going to a semi-synthetic or all the way back to petrolium based? Geez...I really want to pull the engine and do a complete overhaul...

-Darwin

Tom M'Guinn

Where is the leak? I just went back to "high mileage" dino oil in an effort to nurse a few more miles out of my leaky oil pan gasket. I'll let you know if it works.

M758

It is very common to switch to sythetic oil and spring leaks. Syn oil is great for finding oil weak seals. In my 120k mile 951 I run 20 w50 valvoline dino. I don't dare put in Mobil 1 since I know the engine will leak like a siv. I already have leak that is either the rear main seal or the oil pan gasket. Not sure which one. If I let the car sit for a while oil develops on the cross overpipe and she smokes like crazy until it burns off. I'll need to fix one day and probably pull the entire motor and rebuild. This way I can run Mobil 1 and not worry about the next oil leak.

chris951

my car didn't leak anything till I put mobil 1 15w50 in it. Did the same thing to my friend's 951 when he used mobil 1, but I guess that's the price of using synthetic.

Tom M'Guinn

So, for those who have switched back, did the leaks go away after going back to dino oil?

macnewma

From my research on this topic I have found that synthetic can "unveil" leaks in two ways:

1. It removes/breaks down deposits that may have kept the seal from leaking.
2. It either swells or contracts certain seals causing them to not seal as well.

Most say that you could do one of two things if you spring a leak upon switching to synth. You could replace that seal (and probably most other old seals) and continue with Synth. Or you could just stick with a high quality dino. Your call.

Max

FAST44

You could add a quart of Lucas engine oil stabilizer with your synthetic oil. This will also reduce oil usage espicially on track days. A buddy that was using over a quart on a weekend now only uses 1/4 quart.

Zero10

Do not add lucas engine oil stabilizer. It _greatly_ increases foaming, which we all know is very very bad. There was a thread on here a little while ago about that stuff.

Synthetic oil itself will not cause any leaks. It just flows better at lower temperatures than conventional oils do. So, out of the same leak, it will leak more. However, IMO it is a much better solution to find and fix the leak than to run conventional oils. Switching back to conventional oil is just a band-aid fix.

turbinek

I use Mobil 1 5 W 50 and had some loss in the beginning but now it seems to be reduced to a normal loss due to the fact of turbo charger. I have always have an eye on the oil level since there is some X-File about oil loss and spun bearings...
Some points I consider with oil and 951:
always fill in oil really slow so the oil can flow in to the pan and not out of the crank vent
fill in the amount that is missing
check dip stick
if you fill up after oil change with filter make sure everything is back on before you fill in the oil
go through the points (951 needs about 6.5 L of oil)
before you run the engine you might turn starter but dont let engine run so engine just turned a few times instead of 800 to 1200 times a minute
then check level on dick stip again after a few minutes
add if there is needed
then let enigne run and check oil pressure and warning lamp if pressure shows 5 bar and warning lamp goes off after engine start let it idle for a while
check again
then go for a short ride check oil pressure and warining lamp
if no special then drive until oil temp has reached 80 deegri Celcius
shot down engine wait for five minutes and check oil level again
two more tipps always check oil level on an even place - for exact measurements it is best with oil temp at 70 -80 degree Celcius
make sure that the oil level is never under half a dip stick (min to max. mark) as you might chatch an spun bearing
Good luck

Claus Groth

I finally gave up trying to make my engine leak-free. Using Mobil 1 15W50 is most important to me. Anyway, my Maserati leaks like all Italian cars so I am used to it.