The safest bet, (with the least amount of risk of controversy) would be to use a synthetic oil, with a weight of 5w-40. Which brand seems mostly personal preference.
Seems like most owners like either Redline or Royal Purple. Seems like Royal Purple is more likely to be available at your local supplier.
my Ferrari mechanic reccomended using 15/50 Mobil 1 extended performance synthetic. Even though the service manual calls for 5/40. Any thoughts there????
I used to use Shell Helix, but have moved to Silkolene. Silkolene PRO S 5W-40 Ester Synthetic Oil For High Performance Engines
just to add to the confusion you must be feeling at this point , Competizione in Maryland recommends Motul. They are probably the best service shop east of the Mississippi if not in the entire country, so I've followed their advice. Specifically, in my 348 they put in: Motul 8100 5w40 X-Cess Synthetic
Competizione just did an oil change on mine - Motul 15-50 Given their expertise and reputation, I would go with it. I think the premise is the 355 engine runs on the hot side already hence the oil selection.
Potxloi - When my car was up there, Competzione put 5w40 in my 348 too. I think on the following service which was back in North Carolina, Sport Auto put an Agip 10w40 into the car. Car has been running quite nicely, and engine oil temps/pressures seem perfectly normal. The gearbox, with baby-vomit Superlight Shockproof has been nothing short of miraculous. I was a nay-sayer... but now I'm a believer.
Mobil 1 generally rates on the thin side. Their 15/50 is more than likely extremely close to other oil manufacturers 5/40.
How about endowing us with an explanation? As you know, an oil's viscosity rating is a range. Mobil 1 is, most definitely, thinner on the range compared with an identically rated weight of a different brand.
