Long time lurker, first time poster. I ran a search and found nothing, so here we go. I changed the oil in my fiance's 2008 Malibu last summer with Valvoline High Mileage 5w-30. It hit 15% on the OLM about a month ago and I changed it with Amsoil XL 5w-30. The OLM has already dropped to 78% with the same driving. I'm not as well versed as some people on here, so I'm wondering if I need to dump the Amsoil and put high mileage stuff back in. It has 114K on the odometer. I wouldn't have thought that "better" oil would go this quick. Thanks.