How long (time wise) before synthetic oil breaks down?

[sunil6784]

I run Mobil 1 in my car. I changed the oil 3 months ago, but only put 2500 miles on the car. With conventional oil the old belief was 3 months/3000 miles. I know synthetic can run for more mileage, around 10,000 miles, but regardless of miles, how often should you chnage your synthetic oil?

 

[dragnazz5.0]

id change it alteast every 5k miles. it really depends on how well the car runs actually. if you get blowby i would change it at 3k miles. check out www.bobistheoilguy.com the forums over there have a lot of interesting stuff to read

 

[maverick0716]

I heard 6 months somewhere.

 

[vristang]

I'm not sure how long the oil will last.
I would just follow the recommended intervals from Mobil.
Be sure to change the filter every 3,000 miles though.
You don't want any debris plugging up the filter.

jason

 

[HISSIN50]

There's no way to know w/o doing an UOA.

Good luck.

 

[88convert]

HISSIH50 is right, there are a lot of factors that dictate lubricant life...Inlet filtration, lubricant filtration, operating temp. blow by, excessive fuel etc.
The biggest killer of hydrocarbon "oils" is temp.

I know some lubricant engineers from Dow Chemical, Dow Corning, CPI engineering, Petro Canada and DA Lubricants and all agree. If you are using a quality motor oil, changing it at 3-4000 miles is a waste of money. That is, of course is dependant upon the items mentioned above.

A synthetic fluid should be good for 10K easily, providing the items mentioned above are good.

The key is Filtration, Filtration, Filtration

 

[90lxfoxbody]

i agree with everything that is posted above. there is a large number of factors that you have to consider when trying to determine which oil is "best" so i looked for what was "best for me". i had my engine rebuilt at 200,000 miles and i had been using valvoline 10w40 as per my mechaninc's suggestion. after the rebuild i started using valvoline durablend 10w40. it's pretty much half synthetic and half conventional oil. i change my oil every three weeks or 3000 miles religiously. not so much as matter of stirct maintenance, hey i just love to work on my car. anyway, when i change the oil i always run some through a shop towel and check for particles, etc. the oil is always still very slick and relatively clean. so for me that's the "best" oil for my car. if your car is in overall good condition i think 5,000 miles between oil changes with syntheitc would work just fine, just make a point to inpsect the oil when you change. if it looks really cruddy then change the oil at say 4,000 miles and check the difference. if it looks really clean then you might try going 6,000 miles between oil changes. with a little trial and error you can come up with what works best for you.