Old lawnmower ran on Ford semi synthetic 5/30 motor oil for its seven year life, without a single oil change, its demise was (i think) piston ring failure as it was burning oil badly and smoking like a trooper. So with my new lawnmower ( a £150 B&Q briggs engined job) should i use dedicated mower oil this time , or just use the Ford semi synth or any other good quality car engine oil again and maybe treat it to an oil change every couple of years or so.....