So I'm testing out the new castrol edge oil which is supposed to last 1yr or 15,000 miles according to castrol. I'm coming up to my 3k miles that I normally change my synthetic oil at and I'm getting ready to send a sample to blackstone (I didn't have an initial sample because the oil change was unexpected and I had nothing to grab a sample with).

I'm trying to figure out the best way to do this, should I:

1. Do a complete oil change with castrol again and this time go to 7k miles on the new oil and run another analysis.

2. Keep my current oil in the car till 7k but send a sample to blackstone now at 3k and again at 7 to measure changes on the same oil over time. If the results are still good keep the oil and retest every 3k miles until reaching the limit of 15K miles or until the results start to look bad?

Also should I do a TBN test?
http://www.blackstone-labs.com/do_i_need_a_tbn_.html

Any thoughts would be great.

 

As a note here are some results someone posted comparing castrol edge to amsoil. These are virgin samples to use as a base:

Castrol Edge..............Amsoil.....What it is used for
Silicon 3.1.................2.3.........anti foaming agent
Potassium 0...............0............background residual
Boron 66...................19..detergents, dispersant, extreme pressure add
Barium 0...................0.3..........same as above
Magnesium 12...........12............same as above
Moly 129..................220..........friction modifier
Calcium 3509.............3468..detergents, dispersant, extreme pressure add
Phosphorus 823.........810..detergents, dispersant, extreme pressure add
Zinc 941..................848...detergents, dispersant, extreme pressure add
Vis@40C 61.8...........62.0
Vis@100C 10.4.........10.7

 

You'd get a better indication of how the oil is doing if you did a second change, just to ensure that practically all the residual oil left behind when you went to Castrol Edge is removed.

That said, I'd leave the oil in there till say 5000 or 7500 miles, change to Edge again, then do an UOA at 5000 miles...

Yes, test for the TBN. It would tell you whether there is anymore life left in the oil...

Please post your results!