I recently had by Amsoil synthetic tested and though I would share the results. The grade tested was the XL 5w-20. One key thing to note however is I wasn't due for a change on mile, but i was way over on time, Amsoil recommends this grade be changed every 6 months or 7500 miles. I was pushing 12 months on this sample.
Looks as though it tested good even though it was run for longer then recommended. The TBN for this grade starts off at 9.0, and any oil should be replaced by a 2.0 reading, looks as though it still had some life in it yet. Still doing a little reading on the other elements of the test, so I'm not sure how to interpret all the additive readings just yet.
Just looking to share my finding, not start a which oil is better war. Would be interesting if someone tested another brand for comparison, but i haven't seen or missed those threads.
Looks as though it tested good even though it was run for longer then recommended. The TBN for this grade starts off at 9.0, and any oil should be replaced by a 2.0 reading, looks as though it still had some life in it yet. Still doing a little reading on the other elements of the test, so I'm not sure how to interpret all the additive readings just yet.
Just looking to share my finding, not start a which oil is better war. Would be interesting if someone tested another brand for comparison, but i haven't seen or missed those threads.