Mech claims

My car has been very dependable and I am trying to get it inspected for driving in Maine USA. Now the mechanic states that the head gasket needs to be replaced. I do not believe him, as the oil level is excellent, I just changed the oil about a month ago and put in a new oil filter; the oil level has not been a problem since I brought the oil level down to where it should be. Previously same mechanic had overfilled the oil, and I was worried about damage to the gaskets, so I had reduced the oil level so that it does not cause high oil pressure and damage. Now, when I went back to the shop for inspection, they did not pass me, stating that the engine is leaking oil badly, and the oil is going to cause damage to rubber hoses etc. So they want to replace the head gasket before giving me a good inspection approval. I purchased "head gasket sealer" made by Bars Leaks and when the engine had cooled overnight, I opened the top of the car radiator. The level of coolant was all the way to the top of the radiator. The radiator is not leaking; and the oil is not leaking. I see no reason to do any repairs on this engine. Am planning to carefully clean the surface of the engine as much as possible to remove oil and see if any oil reappears from any leak after driving it for several days. (All this time, I am well beyond the required inspection date.) I feel that the mechanics are wrong. This is a 1994 car, but I have never had loss of oil problems. The oil level always stays consistent. (If any damage occurred it was because of mechanics overfilling the oil, thinking that since this is an older car, it must leak oil. Not so. It has never leaked oil. I do not want to replace the head gasket, but would do something like Bars Leaks if this might somehow stop the mechanic from having this so called leak issue. (The car cannot be computer analyzed due to being a 1994 model.) This car drives great. Previously I had a few boil overs but I feel this was during the time after someone overfilled the oil and I think this may have caused overheating. Also, I found that the radiator top was cracked and leaking--and when I finally found a way to seal it properly with 100 percent silicone flowable adhesive, it has not leaked since that was done. First I tried "gasket maker" high temp silicone red adhesive, but it did not hold. The clear silicone, which I used later, did work perfectly and I have had no radiator overheating or loss of fluid or leaks from the radiator since I did that myself about a year ago. So, because the radiator fluid (bright green, which is the same stuff I put in there, mixed with the proper amount of distilled water), is good, and the level has not reduced at all for almost a year, and because the oil level stays good, and is now very clear and the car is not burning oil or smoking, I think the mechanic is wrong. Is there any way to prove this conclusively by some sort of mechanical testing, if not computer testing? That way, I might be able to go back to the same mechanic shop and at least have that issue resolved. I also have another problem. The automatic seat belt retraction mechanism is no good; I had it replaced once before and spent something like $600. I refuse to pay this again, so I replaced the automatic front seat belts with lap and shoulder 3 point manual seat belts, brand new, and they work excellently. (I always use my seat belts, no matter what.) Now, the mechanic demands that I must replace the original automatic seat belts for the front seats! I am so frustrated with this, it is giving me headaches. The car can run another 300,000 miles or more. It runs like a top. Very dependable. The alternator may need to be replaced, and I think I have to replace the fuel filter, but it is a great little car. We paid $10,000 for it in 1994, used (way overpriced, in fact on our payment info from the computer and subsequent records, it appears as a 4 door car, which it is not (it is a 2-door hatchback, but we were charged for a 4-door car). The computer says it has fully automatic windows, thank god it does not. We do have air conditioning. Compression of the engine is holding up quite well, as I used some ceramic coating formula and I believe that may have made it even better and more durable hopefully. Is there any way to pressure someone to get permission to keep the new manual seat belts, as I installed them a few months ago? To replace the automatic seat belts will absolutely drive me over the edge. It is unbearable and stupid, because they are not dependable enough, and I dont need automatic seat belts! (I want to strip out all the seat belt warning electronics also, as I obey the law, and it is none of the government's business whether I use the latest junk gadgets, I am sick of them trying to shove these things down our throats, along with the trillions of dollars "we" sent "somewhere" and have no way to find out where.