I did A LOT of oil testing in a daily beater Honda Accord to find out for myself what the real deal was.
That car got driven about 2,500 miles a month and I did 10,000 mile oil changes.
I tested the following:
Standard dino Castrol GTX
Castrol Edge Synthetic
Mobil1
Penzoil Platinum
Blackstone labs was the analysis vendor used for all tests. I'd run one fill of the oil, then test on the 2nd fill to make sure no residual of the previous was present.
Purolator Pure One oil filters were used.
Even the base Castrol GTX was OK for 10,000 miles use, but was at it's end of life at that point.
All the synthetics were still good even at 10,000 miles with Penzoil Platinum having the best results.
I also found I could go at least 20,000 miles on the Purolator Pure One oil filter as well.
In another car that I don't drive every day I did a one year oil change test on the Penzoil Platinum and it still had plenty of life left in it after a year (only about 6,000 miles on the oil) and same Purolator Pure One oil filter.
In all tests, either none or very little make up oil had to be added. I just sold the Accord test car last week with nearly 200,000 miles on the motor and it had no issues when sold.
All my oil tests are posted over on
- Bob is the Oil Guy.
Every engine is a bit different, and I plan to do some analysis on the 370z to see what it likes oil change interval wise. There's no reason to change oil at 3,000 mile intervals unless you're really tracking the car. I'm gonna start at 5,000 and use Penzoil Platinum with the Purolator Pure One filter and go from there.