I have 3 different bottles (3.2 oz.) of Poulan 2-cycle oil. One of which is synthetic in a grey/silver bottle. Will it hurt my old Poulan chain saw ? I also have an old Lawnboy push mower that I might use it in. And can anyone tell me what the difference between the other two bottles are ? Both are black bottles one has a red cap and I think the other one is blue. Both say "smokeless" and one has a 689 on it. THX.