Further to the recent thread on leaks - is a 100,000 mile engine pushing its luck running fully synth? I'm considering changing next service (98k miles). She doesn't drip much, but it would sure be a cheap fix..
With oil changes every 6k, is FS really still necessary?

Or is it a case of 'Johnnyyyyyyyy. Nooooooooo!'

 

I just had my 90000 mile service performed.......The dealer put synthetic in and I haven't noticed any problems with excessive dripping of oil. The car was recently purchased by me, and I'm pretty sure the PO used regular fossil oil.

My $0.02

 

On my 81 911SC, I switched to synthetic oil at 100K miles, and had no oil leakage problems. Sounds like you want to switch back to dino-based oil?

 

Yes, to clarify, car has had Mobil 1 all her life AFAIK. I would rather she had a dry engine, but wondered if there are any disadvantages to changing. Is it a big backward step?
I know there is lots in search about 'which oil?', but wondering about it specifically as a means of discouraging what is a pretty minor leak..

 

Two things:

1) Excessive leakage with synthetics is very overblown. I suspect the myth got started when people switched to synthetics, and got leaks for the reason in point 2 below. If you switch from synthetic back to mineral, you could have problems.

2) Changing oil chemistry can damage the seals, which are already conditioned to oil used in the past. You might actually cause a marginal seal to start leaking if you switch.

Mineral oils are much better than they used to be. Many (including me) question the need for synthetics in car engines. Switch to save money, but don't expect much difference in leak rates.

I use M1 10W-30 in my 200 K mile E-class, no leaks, and in the 964, no leaks. Both have been on synthetic oil since new, and you can bet I won't be changing brands or even viscosity. I am enjoying my bone-dry garage floor after 26 years with an early 911.

 

Something like this is what I had at the back of my mind. It makes sense. Thanks for the help - I think I'll leave well alone.

 

Johnny - try Mobil1 15w 50 - harder to find than the normal thin stuff, but mine doesn't drip...

 

the best oil is the 10-60W by Castrol (Formula RS). But it is pricey....

 

Christer - does it smell like the old Catsrol R?

 

I don't know. I don't really sniff oil....

 

IRRC, the owner's manual says to use 10W-30 year round. Is anyone aware of Porsche approving other viscosities? Run oil too thick, and you spend a lot of oil pump power forcing oil through the overpressure relief valve. I can't imagine that thicker helps much on leak rates, and I am sure Porsche has reasons for recommending the thinner grades.

 

Springer, i think the manuals recommend slightly different oils around the world...i seem to remember in mine it recommends 10-40 and/or 5-30....i'll hvae to ahve a look....but in my case it doesn't matter as the engine is pretty far from stock.

 

Hi Christer,
yes Castrol RS 10w-60 is an excellent oil. I assisted in its development some nearly 25 years ago. It was called Castrol "R Synthetic" and a 10w-50 viscosity then. It smelled like the old Castrol R caster based product (that was part of its formulation) out of the exhaust - a great smell!!
We "road tested" it in all sorts of petrol and diesel engines and out to 150000kms oil change intervals too with excellent performance and great used oil analysis (UOAs) results

You are correct to consult the original viscosity recommedations - these will still apply. But oil technology/quality is much better now as you will know

RS 10w-60 is a very robust oil with a High Temperature High Shear (HTHS) viscosity of around 5.4cSt
and Porsche's minimum HTHS vis. is 3.5cSt. Anything over 4cSt tends to consume power and of course fuel

The viscosity that is currently used by Porsche - 0w-40 or a 5w-40 (synthetic of course) - is excellent and these oils will typically have a HTHS vis. of around 3.7-4cSt

Regards

 

Ah OK, so in my case it may consume power and fuel, but there is a benefit?

 

There's quite a useful thread here on oil selection