Friction Modifier for 2013 Rubicon??

Need some guidance, Jeepers. I have a 2013 Rubicon Unlimited. I'm about to change a bunch of my fluids for the first time. I'm overdue on my diffs. Who knows (for sure) whether or not I need the friction modifier additive? Most places I'm reading say I don't need it. Dealership says I do. I've already noticed my actual differential fluid is different from the '12 and '14 models (80W-90 instead of 75W-90) So, I'm looking for someone who knows '13 model Rubicon. So torn on what to do...will adding the friction modifier hurt anything if nit needed? Thanks so much!

I run the valvoline synthetic 75 140 and you don't need friction modifier, you have lockers not a limited slip

Thanks, sir. I have an email in to the dealership asking why they would suggest the additive. I've heard the same from others about needing it so I think I have a consensus!

cbohlin said:

Thanks, sir. I have an email in to the dealership asking why they would suggest the additive. I've heard the same from others about needing it so I think I have a consensus!

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If you want the additive all synthetics have friction modifier in them so go synthetic and you'll be fine, but you don't need it with lockers only the limited slips need it