I've run both Mobil1 0w-30 Full Synthetic in my 2004 and Conventional 5w-30 (different brands) and have never noticed an MPG difference. Mobil does advertise it as helping fuel economy, but it's probably such a slight difference that you'd have to track it over a long time to notice.I have used Mobil 1 since day 1. Believe I get better mileage. Average 27-28 mpg, can get upwards of 31-33 mpg on highway, depending on wind, AC, etc.
Link?Engine wear actually decreases as oil ages. This has also been substantiated in testing conducted by Ford Motor Co. and ConocoPhillips, and reported in SAE Technical Paper 2003-01-3119. What this means is that compulsive oil changers are actually causing more engine wear than the people who let their engine's oil get some age on it.
Hate to quote myself, but there is some controversy in interpreting that SAE article:Sorry, you gonna have to google it. The article is old and is archived.
BUT, i wonder if the article may have swayed OEMs into prolonging the oil change intervals on newer powertrains.
This may well be true, although the owners manual suggests more conservative changes, and base their warranty on following maintenance guidelines. I feel short trips in extreme temps are "severe service".IMO, oil changes every 3-4k miles is wasteful. There was an article a while back (link no longer working), but this is what it concluded:
"Based on the results we've got here, we'd recommend 8,000 miles between oil changes on an engine that uses no oil at all, perhaps 10,000 miles on an engine that uses some oil, and 15,000 miles or beyond with a filter change every 5,000 miles. This, of course, isn't any kind of guarantee, and you must evaluate for yourself what your engine requires. One thing we're pretty sure about though: 3,000-mile intervals is a huge waste of resources."
NOTE: this is for Mobil 1 Synthetic. My opinion is that if you're gonna change every 8k miles, then why use synthetic at all?
Hmmm...that's interesting.Here is a good link for further discussions: Compulsive Oil Changers Cause More Engine Wear
And for synthetic fans, here is a long article for your reading pleasures: http://www.mr2.com/TEXT/synth_oil.txt
Yup, that's the extent of my limited knowledge on the matter...you guys can read and decide. For me, even in Texas heat, i am sticking to 7500 mile intervals with regular oil.