Best synthetic motor oil



Looking to make the switch to synthetic for my next oil change. Which brand is best for 5W30?


What specs are you trying to meet (i.e., what brand of car are we talking about)?


Chances are any brand will be “better” and more expensive than what you have been using.

Before we try to figure out what might be better for you, could you tell us what you hope to gain from the switch? For the most part there is no reason to switch to synthetic oil, for a car that does not call for it, other than possibly to extend the change interval.

Being realistic about it, very very few cars suffer from oil problems due to the quality of the oil used, unless it fails to meet the specifications for that car.  Almost all oil related failures have to do with failure to change oil on schedule, allowing it to run low or using oil that does not meet specifications.


I have a 2008 Suburu Outback XT Turbo. A couple of things I’m trying to achieve by switching to synthetic:

  1. Better gas mileage
  2. Less frequent oil changes
  3. Heck, it’s a turbo!!


Both Mobil 1 and Castrol Syntec are frequently used by car manufactures as a factory fill.


AFAIK, your car does not have any unusual oil spec requirements. I like Mobil 1, it’s good quality real (group 4) synthetic, easy to find, and relatively cheap.


Honestly I don’t know if it makes a difference, but elf synthetic motor oil is pretty high end stuff. I’ve heard anecdotally that Mobile 1 comes back from the oil-testing labs with a lot more contaminants than other comprable oils.


From experience, I’ve found that if you ask this question to 10 different people, you’ll get 15 different answers.


Don’t expect to get better gas mileage. I switched ALL my fluids to Synthetic and I saw an increase of 20 miles per tank full. A wopping .3mpg.

Also with a turbo I wouldm’t extend the oil change intervals. A turbo is very harsh on oil.


The main reasons I only use synthetics are easier cold starting in winter and better cold lubrication.


I know the Corvette uses Mobil 1 because they did not want to add an oil cooler.

I know some Porche’s use Mobil 1.

Who uses Castrol Syntech as factory fill?

Does anyone know what Oil Change intervals are recomended by the OEM’s that use the Synthetic?


That can mean at least two things unless we know what kind of “contaminants”. Either the synthetic is better at keeping these contaminants off of engine parts (good thing) or the synthetic is breaking down faster (bad thing).


Stick to a brand thats easily available near you . Stay away from anything that has to be shipped like Elf .


Castrol synthetic oils are used in Aston Martin, Volvo, Jaguar, and the BMW M3 as a factory fill.