Motorhead advice neded: I need to change the original spark plugs in my car after 115k miles. I am told after this many miles the plugs are often stuck fast and will wreck the threads in the aluminum head upon removing the plugs. Is WD-40 as good as anything to loosen stuck plugs or is there any better penetrating oil available? I will be using an anti-seize thread protector coating when I reinstall the new plugs. Thanks in advance.