Hello

I have been serving my 02 I35 with synthetic oil every 5K or half year but in a recent oil change, I was told that I should use high-mileage engine oil and should change every 3k or 3 months. would like to know your experiences or suggestions on this.

thanks

If you have had no issues with the synthetic every 5k, I would stick with that. Most cars on the road today say in the owner's manual that the car only requires the oil to be changed every 5-7k, depending on driving conditions.

thanks for your reply. I followed the manual but last year I fixed an engine oil leak and recently i was told that my engine may burn the oil since the oil has been pretty dark after 3 months with some residuals. this is a commute car w/ almost no highway driving.

Side note, I actually ran an oil analysis test (http://www.blackstone-labs.com/) to see if I could run my car longer between oil changes. I was sticking to 6k-7.5k between oil changes. After running the tests, the comments on the report said since the (regular) oil still had some life left and I could run my 02 I35 10k miles between changes, but that I should probably stick to 7.5k to be on the safe side. My car currently has 145k miles and I don't use high mileage anything.

Just my two cents

Oil turns dark due to blow-by gas from the piston rings and carbon deposit in the engine. The best way to find out if you have the correct OCI is to run an oil analysis as recommended above by 'chillin'. I used to have 4,000 miles/4 months OCI but switched to 6,000 miles/6 months after oil analysis from Black stone. I use Mobil 1 synthetic. I could have extended the OCI if I wanted to. I also have a bi-annual maintenance where all the fluids are replaced. All 5 cars are running great.

I just received my kit from Blackstone. I believe that an analysis is the only way to really know what's going on. Next oil change, I'll be sending them a sample to evaluate. Forget colour, odour, etc.