I have about 8 qts of Exxon Elite oil on hand that was bought back in 2006-2007. It's from a case I bought, then sold my plane before I used it. Is there any reason it wouldn't be ok to use it now? My engine is ready to go to regular multi weight oil now, and I thought I would change the oil today, seeing as there's no work today (for me) due to power outages here in CT.