Crank but no start and a milk substance in the oil

One day I went to check my oil because I had noticed it tends to use more oil now days to where I will need to add more oil before my next oil change. I noticed a little spot on the dipstick where it kind of looked like a little bit of a milky solid color substance on as well as the dark oil, it kind of had a burnt smell to it at which I thought it smelled like kerosene, but someone else said it smelled like gas. As I continued to drive it (not acting much different than before) it’s slowly progress little by little not amounting the much. Well, it came time to change my oil, so my my father and I had done. So, I had got 6 quarts synthetic Valvoline high mileage 5w 30, 1 quart. Lucas oil stabilizer, and the oil filter- fram- xtra guard. So, a couple weeks after we changed the oil filter and all I had checked the dipstick for anymore milky substances sure enough there was and there was actually more on it than ever before which came odd to me I would think there would be more on it before more so than after changing the oil so I assume there must be a leak of something somewhere going into my oil and can that be for the reason that my car mysteriously one day I started my car and left to go to the store at which when I started it didn’t have no funny start nothing different about it, I get to the station i’m pretty sure I had turned my car off if not I left it running to go in real quick and come back out then I jogged over to the store and I turn the car off and did what I had to do in the store came back out went to start it and all it would do is crank over but not start so I pop my hood checked my battery cables my ground had a lil corrosion so I took it all apart and cleaned it put it back on tried starting it again.

Still to this day it only wants to crank over and still to this day it will only crank over although I do have an old battery from 2017 the sticker says but if it was due to the battery I wouldn’t have no power, right? A couple months ago I had change the alternator (i used one from a junkyard but it looked barely used) because I had no crank no start issue which was the terminals being corroded! I have full power in my car still to this day I went out there earlier to try to start it and it still only cranks over. Do you have any idea of what could be wrong with it, other than my tough old little Bernice is getting worn to her core? If I remember correctly there was an ignition switch recall on it that I never gotten replaced because the lady said asked me if I had a key that had the black plastic piece on it. I don't so the lady said I had to purchase one from them in order to get that replaced because all they do is put a chip in the key! She informed me to not have a heavy set of keys while the key is in the ignition! So, I figured it really wasn’t that important to have to go buy another key for the car that’s seems to be on its last leg! Don’t get me wrong, she has been a reliable car for quite a few years. Has a bit of electrical issue sometimes but had still been pretty reliable! Let me end this with showing you my appreciation, whether or not you can or can’t help me! Here’s for you a please and thank you for your assistance and your time! Have a great rest of your day!