Yesterday, my younger brother took a break from his beamer to give me a hand changing my oil. I have never changed the oil in my '96 MX-6 M-edition myself; I usually entrust it to the shop. Apparently, what my brother drained from my engine wasn't oil. While driving ~80mph, the car shifted itself out of 5th into neutral. Also, in second and third, the car makes a high pitched whine that sounds kind of like reverse gear does.
If anyone could offer any insight to what exactly he did to my car, I'd appreciate it.

 

he probably drained your trans fluid

 

sounds like a pretty good guestamet Boomer27!!! Better check the trans oil level before driving again or you may get or already have some permanent trans damage. The engine oil drain should have been on the more right side of the engine area and take a 19mm wrench to remove. The trans drain is a 23mm plug on the more left side. Checking level is tough as you have to remove the speedometer driven gear to refill and check. Follow your speedo cable down from the firewall to the trans and unscrew cable. Remove driven gear retaining bolt with a 10mm socket wrench and pull speedo gear from trans. should be able to get gear oil on the tip of your finger when finger is down in hole up to the second knuckle. If none felt then drain trans and see what is left inside. Little Bro may owe you a transmission!!!!

 

I just got my first Mazda, 1991 MX-6, found the forum and joined. Your post is several months old, and you probably rectified your problem already. But a suggestion from a 15 year user of Lucas Oil Stabilizer. If you are not familiar with this, and even possibly damaged your transaxle with premature wear using regular oil, drain a quart of fluid from your transaxle, add a quart of Lucas Stabilizer, you will not believe the difference in operation and extension of useful life you will receive. If you are not familiar with the product, you can read about it on the Lucas Oil website, or go into most any parts house and observe the demo toy they have on their counters. It is the one where there are 2 sets of gears, and external cranks. Crank one side, with regular motor oil, you'll see the oil run off quicker than you can crank. Crank the other side, with Lucas, you will see the oil sticks to the gears, and in fact the gears were probably coated when you first walked up to the counter. If you get the stuff on your fingers, you have to grind it off. It is 100% petroleum, no teflon or other foreign materials, just petroleum. It is thick, like STP, and actually is designed for cold-start protection on crankshafts, to extend engine life. I have used it in a dozen cars, some old and completely worn out, you cannot believe the difference. It penetrates muck, if there is any, and clings to the metal parts, and stays there. You cannot wipe it off metal, or your hands. I usually microwave the plastic bottle about 10-15 seconds before using it, or run VERY hot water over the bottle before I pour, and it comes out easier. To get it in the transaxle, you might have to use a funnel and plastic tubing or plastic air line like they use on 18 wheelers, but it will be worth the effort. No, I don't get paid by Lucas, I just believe in this product. You can use it anywhere your vehicle takes lubricating fluid. I run it in power steering, rear ends, transmissions, and crankcases. I learned this trick from stock car racers I used to hang with.