R
Richie
Guest
i have 94 mustang gt 5.0.under my hood it says to use SAE 10w-30 oil.since i've owned the car i did two oil changes useing 10w-30 synthetic oil.my question is will it hurt my motor if im useing fully synthetic oil if my car doesnt call for fully synthetic? since ive done my fisrt change ive noticed that my motor bogs down and the valves chatter. any help with this will be great