Changing syn oil every 5K?! That's an utter waste of mullah and resource.
typical off-the-shelf Gp 3 or higher "syn" oil in NA, can easily get to 7~8kmiles w/o any issues (still some respectable TBN left). doing 5K OCI using these excellent oil is (esp. on OBD-II engines) is just like nowadays quikkie lube still encourages changing average conventional oil every 3k ....
I now pushes 5K for conventional API SN/ILSAC-GL5 oil on all the vehicles I maintain/service; and up to 9k on syn.
Q.
typical off-the-shelf Gp 3 or higher "syn" oil in NA, can easily get to 7~8kmiles w/o any issues (still some respectable TBN left). doing 5K OCI using these excellent oil is (esp. on OBD-II engines) is just like nowadays quikkie lube still encourages changing average conventional oil every 3k ....
I now pushes 5K for conventional API SN/ILSAC-GL5 oil on all the vehicles I maintain/service; and up to 9k on syn.
Q.