Cleaning the MB 100 starter motor and fixing its battery

Car batteries are very expensive now a days. It ranges from 4 thousand to 5 thousand per car battery (12 to 15 plates) specifications. The two cars needs battery replacement. Their batteries last until 2 years and 6 months and It performs very well. The Battery of MB 100 is Motolite Gold that cost 4500 while the Toyota pick up is having an Outlast brand with thirteen plates. I bought the new Mega force15 plates for my Diesel type engine. It cost 3800 pesos. I installed it right away after I arrived in my house. After the installation , I tried to run the engine but it doesn't fire. there must be some loose contacts in wiring or a trouble in the part of the starter motor. I dismantle and took the starter motor assembly and inspect it manually. I have notice that there's no wrong with it but it was covered with grease and sticky oil so I performed cleaning and degreasing. I wash it with gasoline to wash away the grease and unwanted oils from its body. I also check the wiring's that connects the starter motor from the positive cable. Then I installed it back. After installing it back, I start the engine and it fires and runs smoothly. In order to keep the engine in good condition you must keep the engine clean and free from oil leaks and dust.