Do all 350s come with Mobil-1? If not do most owners use a synthetic oil like Mobil-1 and does it improve the MPG?

 

No, they do not come from factory with Mobil 1 . The MPG shouldn't be any different due to synthetic versus dino oil. Mileage improvement comes from the viscosity of the oil (5w30 would yield slightly better MPG than 10w30). One other thing to keep in mind is new ES350 takes quite a bit of oil. As per owners manual, 6.4 quarts including the filter change !!

I used to use Mobil 1 in my 02 ES300. Generally, the synthetic oil will excel in the extremes. It flows far better in the colder temperatures (especially at startup) and is much better protection against the heat (think 90-95 degrees outside with your A/C turned on). That engine is getting mighty hot inside !

 

I haven't changed the oil in my 2007 ES 350 yet but I always used a synthetic oil in my 2000 ES 300. I don't know that it affected mileage but I feel it helps keep the engine in better shape.

 

No the car comes with regular oil but its good to change to synthetic because there are more advantages to that(ie heat displacement, cleaner engine, less combustion, no varnish) BUT if you are thinking about changing to Mobil 1, i would advise you to switch to Mobil 1 Extended Performance because looking at the used oil analysis on the regular M1 ever since they started meeting the ILSAC GF-4 SM requirements, the bearing wear(lead, copper) has increased and so has the iron levels(pistons?). There is a guy Terry who ownes Dyson Labs which does UOA's and hes hinted plenty of times that M1 is not the same oil it used to be. Other good synthetic oil's are Amsoil(anything but the XL), redline(best IMO) and the recently released Pennzoil Platinum thats been giving superb UOA's thus far.(I think PP is a Grp. III hydrocracked synthetic but am not positive)