Quote:
Originally Posted by m4a1mustang
I use Redline and am not comfortable taking it too far beyond 4k-4.5k miles under regular driving conditions. It may very well be good beyond that (and probably is), but at 4k I'd much rather replace the dirty stuff with clean and go on with it.
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Get a UOA done, see if the viscocity has dropped by much, see if the TBN numbers ok. You might find you can go for a while longer, and if you can you'll earn the UOA cost back pretty quickly, if not you have the satisfaction of knowing your suspicions were correct =) you win both ways.
Seeing that you're basically using the best oil out there i reckon you'd find that your oils doing fine after 4k... though i don't know your driving style or the areas you drive your z.