Hello there...i bought my car with 23500km...Previous owner used mobil1 0/40 until 20000km (he changer them at 7,14)and then replaced them with redline 5/40...i switched back to mobil 0/40 at 26000km,two weeks ago...The problem is tha when i start the car after a few days of garage sitting it makes a horrible noise (probably from lifters?)such as there is no oil for about 1/3 of a second and then oil pressure goes up and the noise stops...engine is running fine...With redline this noise did not happen...any ideas?
P.S. the car has almost no oil consumption...

 

turn ignition to on..and wait a few seconds (3) before starting the motor.

 

I ll try that...But what it does?

 

It gets hot in Greece, maybe 5w50 would work well there. That's what I use.

 

some said 0w40 for normal use and 5w40 for hot weather with aspiring driving use.

 

I immediately noticed my engine running smoother with the 5w-40 oil (I use Lubromoly by the way). I was rather shocked about all the little "noises" the engine used to make before the switch...they simply disappeared after using the 5w-40. For what it's worth, I know many folks who also use a 5w-30 grade oil (although not recommended by Porsche). The 5w-40 grade shears to a 5w-30 after about 1,000 miles anyways...Mercedes Benz V12 bi-turbo engine calls for a 5w-30 which I thought was interesting...

 

might allow some pre-start oiling to occur

 

We run 5-40 redline in all of our high hp cars.

 

I ditched the 0w-40 Mobil 1 for Pentosin 5w-40. The car does seem to run better all around. (cold, hot, not as noisy) This recommendation came from David Laing at GrandSport. Pentosin is approved by Porsche. If anyone has any questions why I'm sure he would be more than happy to discuss with you. http://www.grandsport-michigan.com/home.html

 

thank you all guys...

 

Absolutely nothing. The oil pump/s of the the engine are not electric and begin working when the engine is physically turning over either by the starter or under its own steam.

If your engine is making lifter noises on factory spec mobil one then that could be due to a number of reasons. Adding thicker oil usually helps to compensate for worn components by quietening down excess running clearances. The low mileage of the engine is inconsequential if it has been subjected to abuse,high combustion temperatures, and/or poor servicing regimes.

 

i am trying to figure out whether an engine that uses 5/40 oil for 4000miles and then changed back to 0/40 has "learned" 5/40 oil...Yesterday i started the car in order to video tape the noise...but it was silent... we will see...i really dont know if the 5/40 had any additives that are missing now...

 

has anyone tried a 0w-50? it seems like that would give you the best of both worlds: http://www.chrysanstore.com/enmooil0wgra.html

http://www.mobil.com/USA-English/Mot...ing_0W-50.aspx

 

No, engines dont "learn" oil. Heavier or more viscous oils are often used to mask an excess running clearance problem but eventually these kinds of noises will continue to re surface unless you keep thickening the oil with additives. It really depends on what the actual problem is (that is if there is any here) and, if there has been any scuffing anywhere at one point that damage will eventually cause the affected components to fail anyway. If your engine is now silent thats a good sign but id still check what your oil pressure is doing when the engine gets to normal operating temperatures after a good run. If it is sitting a bit below the minimum then thats not a great sign. You obviously have concerns so look for the obvious signs when the engine heats up such as lower than normal O/P, abnormal smoke, smells, sound of engine etc. I Hope its fine..