Our family has two cars: - an 05 5 speed Vibe with almost 50k miles which has had *only* synthetic engine and transmission oil since almost day 1. (I have done several UOAs for several different oils on this car. I am just over 6 months and 3600 miles into a run of PP5 5W30) - a new Chevy Traverse with the GM 3.6L VVT DI engine. (I changed out the FF at 500 miles; changed out QH 5W30 at 1500 miles http://www.bobistheoilguy.com/forums/ubb...rue#Post1494396 and am now on a basic 3k OCI, again with QH and again with a PF48) Starting this fall and then for the rest of a Canadian winter both cars will see daily use but for low mileage consisting of short trips. Specifically during the work week each will go maybe 2 miles to a parking lot, sit all day then return home that evening. So it is often that neither will get to operating temperature during the week day. This scenario is ripe for fuel dilution for both vehicles but especially for the DI engine. In my stash I have the following oils: - GC - QHorsepower 5W30 - RLI 0W30 - Castrol SLX Professional 4718M (5W30) I will be changing out the current PP 5W30 in the Vibe (a 6 month OCI) in the next week. My 3k mile run of QH 5W30 for the Traverse will likely be completed mid to late August. I am for sure open to suggestion. That is from my stash which oil would you choose for which car for their upcoming oil changes? (I dont think I am too concerned re the warranty for either car given that some of my stash isnt GM approved. I have a significant supply of the QH with receipts). Of course the Chevy has the OLM but given the scenario should I just change the oil on both cars after 3 months regardless of miles driven (Vibe) or OLM (Traverse) due to the likely high dilution? Can one consider any oil better than another in protecting an engine in the presence of fuel? Thanks for your advice.