Engine will not crank

As someone who knows better but spent many years strapped for cash, I ignored oil changes in my car for probably close to 90,000 miles. The car began producing what appeared to be smoke from the tailpipes, however, unlike the bluish smoke you would see with oil burning, it was white smoke and was only noticeable at idle or when stomping on the accelerator. The oil level was okay, however upon removing and checking under the filler cap, the engine had nothing but sludge, the consistency of grease.

I found a sludge removal product called Auto-RX Plus, online and followed the instructions for extreme sludge removal. It involved adding two 12 oz. Bottles of the product along with an oil and filter change. The car was to be driven for 3,000 to 4,000 miles before draining the crankcase, adding new oil, and changing the filter. The treatment was finished upon driving another 3,000 to 4,000 miles. For heavy sludge, it was recommended to follow this treatment twice.

I added the product while changing the oil and filter and almost immediately it stopped smoking completely. I drove it for 4,000 miles, recommended synthetic oil, and did the oil change and filter. The car ran fine, the sludge appeared to have cleaned out for the most part and it didn't smoke anymore. I was going to do another treatment at the end of 4,000 miles. However, after about 3,000 miles I was on the Interstate headed for a family get-together when suddenly the oil light came on. My destination was about another 5 or 6 miles so I decided to continue on. Upon getting ready to leave our destination, I checked the oil, and it was empty. I couldn't understand that because it was not smoking, and I had no leaks. Fortunately, I had five quarts of oil in the trunk, and I added it all to the crankcase.

Upon starting the car, the oil light never went out, but it seemed to run fine. I continued to drive it that way for probably another month when I noticed that the engine was missing now and then. It was still running when my daughter borrowed the car to go on an errand and come home. The next morning, she had to use the car again, however when she went to start it, the engine would not turn over. She indicated that it had been working fine when she used it the night before. I thought about the engine being locked up, however, I couldn't understand how an engine would lock up when all it was doing was resting there and not running.

So, on a chance, I decided to replace the starter. Well, a new starter would not turn the engine either. To be sure that it was locked up, I attempted to manually turn the engine and I was successful at doing so. I then tried to start the engine and it did turn over and start, but it was missing so badly that it would barely run for more than a few seconds before shutting off. I repeatedly started it quite a few times but eventually, it would not turn over again. Due to a lack of funds, I have not had the opportunity to get it checked and I fear the worst. It has now been sitting in the driveway for the past 2.5 years and I have made no attempt to start it again. I have since decided that the oil pump failed that day on the Interstate and nearly a month of driving it that way most probably destroyed the engine even if it wasn't completely locked up. Or, maybe it could be something else.

In your professional opinion, does it sound like I most probably need a new engine? I apologize for the length of this problem description, but it does say "Be as thorough as possible." :D

On the next page, it asks for "Level of experience". There is no answer that would apply to me. I would have been categorized as "I am not a mechanic but know a lot about auto repair" if you were talking about vehicles before fuel injectors but know very little about engine work nowadays. However, I can do relatively minor repairs and maintenance such as changing pads and rotors, ignition coils and spark plugs, starters, alternators, radiators, and all that kind of stuff.

Thanks,
Mark Gerber