What is the ford ranger rear differential fluid type?

The Ford Ranger rear differential fluid type iS75w-140 synthetic lubricant. This part will need to be changed eventually. You should change Your tires every 30,000 to 50,000 miles or so. You don't want to get into any accidents on the road. Making sure Your tires are in the best condition is key to not crashing. You will come into problems with this part at some time or another. Check for holes, in case You run over something sharp. The part might become loose at some point. Premature tire wear is something to be on the lookout for. You might run into feathering issues. You could face cupping problems. Make sure to inspect the tire pressure once a month.