I don't think using a quart of oil every 3K miles would be considered excessive under any warranty program. About the only thing the dealer will do is look for a leak...other than that I think your other option is going back to dino oil assuming of course it didn't use any before you switched to synthetic.

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99 E300 133K
98 ML320 99K
87 Saab 900 Turbo Conv 123K