Switched to 5w-20 Mobil 1 and now my mileage has dropped?
WTF! I changed my oil yesterday. I normally run Castrol GTX 5w-20, 2009 Hemi, 19,000 miles
I decided to try synthetic so I went with Mobil 1 5w-20 and a WIX filter.
I drove a 300 mile round trip yesterday evening that I have done many times before and I always average around 17.5mpg for the entire 300 miles. This trip was different, i barely got 16mpg
I ran the cruise set on speed limit for the whole trip like I always do, there was no wind, very little traffic. 70mph on the highway, 55mph on the back roads, only one town to drive through. Conditions were about the same as always. Fifty degree sunny mountain weather!
I would have thought that the syn would have at least netted me the same mileage if not better.
I was told by my dealer that the MDS/VVT likes the syn better and will hold in 4cyl mode slightly longer with it.
I'm going to try the syn for one more change and if I continue to see the mpg drop I'm going back to dino oil.
Anybody else have this issue?