Engine will not crank or turn over

Okay, lets do the basics first before we throw blame elsewhere.

Grab your battery clamps on the battery posts, can you forcibly twist, pull, make it move the clamp on of the battery using your hand?

If you have aftermarket (regular ole) clamps whereas a two hole strap holds the cable to the clamp. Let's "left and right" the cable forcibly. Does the copper on the other side of the strap move? (it should not!)

Your starter solenoid (now days called a starter relay) body should be bolted on to a good clean ground (fender).

Now for the good part, I always try to shorten this but get the message through.

Clean the battery posts and inside of the battery clamps. Tap them way down on the battery posts. Tighten well (your clamp should still have a gap when you are done, not the clamp ends touching and the bolt will go no further). (This depends on the type clamp you have). Again, you should not be able to bare-handed-ly move a battery clamp on a battery terminal!

Now follow the positive and negative cables from the battery and the cable from the starter. When you find their destinations, check the tightness there.

Clean (or at least loosen and scooch the ends around) the cable ends and the posts they connect to. (both sides of the solenoid, the starter connection (these all being the hot cables) and check the ground from the negative battery cable. Tighten everything well.

Many folks halfheartedly do these things, they will touch the items with their hands but never actually get in there and wrench on them!

Here is a link from our site (repair guides-top right of our pages):

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

Here are some pictures I made.

Keep us posted on progress,

The Medic

Just guessing everything worked fine before the batteries being replaced.

Maybe you replaced the batteries and it was a starter problem all along?

My guess is the oil was present before this issue.

I do not think that either starter for that truck (longer looking type or the shorter Nippondenso) would be affected by oil around the drive gear.

Insure you have not swapped battery cables around the wrong way and have the starter tested at an auto parts store.

Keep us posted.

The Medic