I bought my rear Magtec directly from Magtec and the guy told me to not use royal purple bc they were having issues with the Magtec material and RP not getting along. Can't remember the exact reasons but you could give them a call for clarification. Recommended Mobil 1 Synthetic.
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2006 Mega SLT - Carli Starter - Carli trackbar - Fox SS - Magnaflow custom dual 4" - K&N Intake - Magtec tran pan rear diff. - PacBrake airbags - Moto Metal w/ 35x12.5x20 Toyo M/T - Smarty Jr.