Oil

i would stick to conventional oil there is no benefit in using synthetic with the mileage that is on your vehicle ive seen 2 vehicles that were high mileage that switched to synthetic that developed a knock in the lower end and ended up having to replace the engine

Do you think that could happen if we only used it for this oil change? Also, I'm not sure if conventional has been the only thing used. I know for the past 3 years that's what has been put in because that is when we purchased it. Prior to that I'm unsure.

Ok, thank you for the response! I will probably return it. I live about 30-40 minutes from where we have to purchase it, so I was trying to avoid that, but would rather suck it up than risk harming my car! I guess this will teach my fiance to send me to get these things haha

I just contacted our local auto parts store because I was just going to suck it up and pay the higher price and return the full synthetic next time I'm in that area. He told me not to worry about it because anything below a 10W has synthetics in it so technically my car is essentially using synthetic or semi-synthetic oil already. Does this sound accurate? That is what I understood, but I could be totally wrong.