I agree with you BigJames. If you fill the bores up with oil and put the bolt in then you may break the bore out. Also the guy who put silicone in the bore was probably trying to seal the bolt on a water cooled engine. This can also blow the bore out. On the small air cooled engines you should have a clean bolt and have ran a tap in the bores to make sure all is clean. Then blow out the bore and put a coat of engine oil on the bolt threads only. Then put a small amount under the bolt head. This is the correct way to do it with no problems. If working on a water cooled engine where the head bolts are wet (penitrating into the coolant) then clean as said and apply copper coat to the bolt threads only and a touch of anti-seeze under the head. If it is a dry bolt then treat it like it is an air cooled engine. When in doubt check your manual.