Synthetic Oils

[RyanZ71]

For those of you whom switched over to Synthetic at higher miles, say over 70,000 miles, did you notice any problems?

[tinman]

I started using Mobile 1 in my truck at 7500 and 10000 for the wifes truck

[Markeaux]

On both my old 91 LeSabre 3.8L and current 00 Grand Prix 3.8L (both purchased used, 60Kmi and 40Kmi respectively), right after switching to Mobil1 the pan gasket leaked profusely. However, I've had no leaks after switching other vehicles, usually within a few thousand miles of new.

[JayMan]

I switched mine to Mobil 1 at 1,200 miles. I use Mobil 1 0W-30 in winter (Can get down to -42 F) and Mobil 1 10W-30 in summer.

 

There really is no such thing as a "break-in" anymore. Modern motors are machine assembled and run on dynometers to do QC checks and to quickly seat the rings. Otherwise you'd never meet OBD2 federal and CA emissions with a brand new motor.

 

The GMPP (General Motors Performance Parts) suggests a 500 mile break-in procedure.

[J-rod]

My first oil change was to Castrol Syntec (the full, not the blend). I think I used that for 2 oil changes and noticed minor CSK from time to time. Well, in talking with other synthetic oil users, many of them recommended Mobil 1 so on the next change I switched to it. I haven't noticed the CSK since! (currently at about 30k miles)