how long does synthetic oil last for? had the same oil in my car for over 9 months but only have about 3.5k miles on the oil

mobil 5w30 supersyn

 

i change my oil every 3000 miles...I'm sure running some fresh oil in your car will make things run smoother.

 

I use the same and go 5k between changes. That's one of the advantages to synthetics, more miles between changes.

In the end, it's whatever helps you sleep well at night. Earlier than 3K is a waste, so anything after that is fine.

Cheers,
Roy

 

well its reccomended that you change it every 3 months or 3000 miles whichever comes first...they usually reccomend that for extreme temps...high heat low low temps....personally i burned oil pretty consistantly so i just changed it every 3 months