I have suggested two of my friends to try the new PP as they are running a lot of rebates recently. But both of my friends seems don't like PP. One is 95 Nissan 200SX, same as Sentra, with around 160K on clock. He can hear more noise from engine when he accelerate. He used to use Mobil regular Syn. Another friend with 97 Nissan Sentra, with 70K on clock. He feel the same thing. He used to use Mobil EP. Any comments?