it could be a injector, but also could be a a lifter with a 150,000 i don't think it would be worth the fix, as syn verses mineral oils that's a matter of opinion. the big differents between the both is syn is cleaner right from the bottle were mineral oils can have as high as 20 Microns particlesticals in the oil. i have battled with mobil oil over contaminates in there mineral oils with proof from oil analysis with little results so thats the main reason the company i work for switched to syn. and also sys will last longer before breaking down but the price of the oil is higher