when I had my 05 rubicon, I tryed the royal purple syncromax in the 6spd, didn't really make a difference from stock. When I had my 02 Dodge with the cummins, its 6spd. used the same stuff. I tryed the royal purple in that again, and it actually seemed worse than the stock stuff. Next time around, I tryed Redline MTL in it, and it was like a night and day difference. Maybe you wanna give that stuff a shot. SummitRacing sells it for like $9 or $10 a quart I think.
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