I would like to know if any GXP owners are having oil leaks and what type of oil you are using. I’m at 27k miles, and my engine has no leaks, not even a slight smell of oil, and I want to keep it that way. I decided to run conventional oil for a nice long break-in to loosen up the motor before switching to synthetic. I’ve done that now, so I’m ready to switch. My only concern is that oil leaks are more likely when switching to synthetic. I despise any type of oil leak.

If I go to synthetic on this oil change, I am considering using Royal Purple, as it is a full synthetic. I do currently use Mobil 1 in my 2.3 turbo. It works fine other than several oil leaks.

No leaks here running full synthetic. I did have a issue with the oil cooler lines tho, Before the switch.

35k. No Leaks. Not synthetic

Just as a side note...you can break in an engine just fine with synthetic. And Royal Purple is sort of a waste of money. No significant benefits to right the cost.

42k miles, no oil leaks I prefer to use Mobil 5w30.

I also had a slight oil leak when I first got the car at the oil lines going to the oil cooler. The Opel dealer in Germany replaced the O rings and all has been fine since. 53,000 miles of "very spirited" driving on the autobahn and all over the U.*.
I've used synthetic since new and all sorts of brands.

Thanks guys. This is good enough for me; I’m going to switch to synthetic, and I will sleep just fine.

As far as the engine breaking in just fine with synthetics, yes it will. There is some debate about this if you are talking about initial start-up, depending on the rings and cylinder wall finish, but certainly after the first few hundred miles the rings are seated and it’* a non-issue.

However I do feel there is potentially a slight performance advantage that can be attained by getting the engine well worn in and loosened-up before switching to synthetic. Many vehicles run quicker in the ¼ mile at 20,000 or even 50,000 miles than at a few thousand miles. Admittedly, it’* just a guess on my part as to what the effect this will have on this particular version of the Northstar engine.

None here with 37k and using Mobil 1.

I just used the OEM oil for breakin and dumped it at 1000 miles, it was a rough break in . I have used Castrol Syntec since and use the oil monitor as my guide. There is a ton of info now coming out that shows synthetic protects better after 3,000 miles. So why waste money. My oil monitor has been giving me 8-9k miles before oil life is used up. I am presently at 22k miles and not a trace of a drip of oil. Oil consumption was high in the beginning but that has diminished to almost nothing now. I quess I finally got the stubborn N* rings to seat.

40k no oil leaks using reg oil