I bought the Mobil1 cap because I had an argument (no kidding a friendly argument not a bad one) with the service manager at the Buick dealership. Dealership is not far from my office so I take the car there for work - they take me to-from the office. Such a deal....
Anyway - argument was that I always use synthetic oil, usually Mobil 1. They did an oil change and put regular oil in. Actually you can hear/feel the difference. I took car back, they admitted using dino juice, I pointed to work order where the service writer had in fact written to use Mobil1, they changed the oil (again) to Mobil 1.
The next time I had the car in, I think for a tire changeover or some such, they put a "MOBIL1 ONLY" factory sticker (I traced the part number - it's the sticker they use on the Corvette and other cars with the Vette engine) on the cowl. I did not know - I confess it was more than a month before I knew. I was topping off washer fluid or some darn thing and found it. I had a good laugh. Next time I was in I told 'em they got me.
So when I saw the Mobil1 oil caps on gmpartsdirect for cheap, oh sure, I bought one. I used a label maker to put the right grade (10W-30) stamp on it (they were all 5W-30). Next oil change they spotted it, and we shared another good laugh.
I have not figured out how to get them to use the PF-52 filters consistenly, though.
Albertj
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1998 with all fac. opts. (exc. CD changer and subwoofer); 209,000 miles. Mods: KYB front struts, extra noise barriers, fire extinguisher, Magnecor 8mm plug wires, 4-note horn, custom-made stainless exhaust.
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