Welcome to GenVibe! Very sorry to hear of your mom's passing, but it's neat to hear that driving her Vibe makes you feel close to her.
As far as synthetic oil, I personally have used regular old Penzoil 5W-20 in both our 2009 Vibe GTs since new and haven't had any issues. I really don't see the point in using synthetic as we've had quite a few vehicles over the years that we have easily gotten 200,000+ miles out of using regular Penzoil. IMO, it really comes down to personal preference.
As others have said, my best recommendation for a little extra power is an intake. Whether your Vibe is a 1.8L or 2.4L, K&N makes intakes that will fit both engines. K&N's intakes fit great, increase power and gas mileage and give the engine a bit more aggressive tone. They can be had on eBay for under $250.00. I have had a K&N intake on my 2009 Vibe GT for almost 3 years now and I still love the sound it provides! I have seen a steady 1-2 mpg increase and it looks much better under the hood then the stock stuff.
As far as accessories go, we have the GM premium all weather front and rear floor mats (#19170829), 2 GM premium all weather cargo mats (#19170827) and the GM rear cargo security shade (#19171208) in each of our 2009 Vibe GTs. The floor mats have been discontinued, but contact
GMPartsCenter.net, they should be able to get you a set no problem. I will never have carpeted floor mats again. It's so nice to be able to remove the mats and simply spray them off with the hose. Plus, they look nice because the front ones have the Vibe and arrowhead logos. I purchased a 2nd cargo mat for each Vibe earlier this year to protect the backs of the rear seats when they're folded down to haul things. Again, if something gets spilled on the cargo mats, it's nice to be able to remove them and simply spray them off. As kincaid said, it also keeps things from sliding around in the cargo area. Finally, the cargo security shade is nice because it hides stuff you may have in the cargo area. Both our Vibes have tinted windows, but I feel even safer having the extra protection of the cargo shades as well.
Here is a link to all the available GM accessories for 2009-2010 Vibes. Anything you may decide to get, I recommend ordering from
GMPartsCenter.net as they have free shipping and the best prices on everything GM. Click on my signature picture to visit my Garage and see pictures of all the GM accessories I have.
Last but not least, post pictures of your Vibe when you get a chance

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