Lock washers could be considered the root of all evil in the life expectancy of a starter.
Most lock washers today are manufactured off shore with inferior metal and inefficient galvanizing metallurgy. Modern day consumers flock towards the cheapest price they can get. This encourages suppliers to lower the quality standards of their product especially in larger big box store chains. We have found it nearly impossible to buy a high quality lock washer.
Being that the lock washer is constantly subjected to polarity (+) may also compound the tendency to corrode. Shortly after being installed in an electrical connection, the average lockwasher begins to corrode. As the corrosion sets in, resistance is created from the corrosion. As the starter is used, heat is caused by the resistance. Then, heat causes expansion which loosens the connection which causes more resistance and increased heat.
As the heat on the metal cools, it condenses moisture from the surrounding humidity in the air which also contributes to the bad connection because once the galvanize breaks down, it allows oxidation (rust) to form. It is our finding, over the years, that the lock washer in an electrical connection is like a snowball effect on a slippery slope in a vicious cycle.
corrosion——> resistance——-> heat——–> rust ——-> more corrosion—–>
more resistance——-> more heat———>more rust——->
Then, the low voltage ruins the starter and solenoid because of the increased amps output from the battery.
We have discouraged the use of lock washers in an electrical connection for the last 4 decades. Plenty of dielectric grease and 2 wrenches (one for the bottom nut and one for the top nut) has always been the best recipe for starter and alternator longevity.