Mitsubishi Repair: 97 GS Manual Transmission Rattle, transmission lubricant, gear lubricant

Question
I just got a 1997 Eclipse GS for Christmas. It has about 110,000 miles on it. There is a rattle in the transmission that neither my Father or I can figure out. We do know that it has something to do with fifth gear because it doesn't make the noise when it's engaged. Nor does it make a noise when the clutch is in. We believe that the transmission lubricant we are using is to thick and fifth gear is getting insufficient lubrication or none at all. The noise stops, after the engine and transmission are warmed up, at idle and all gears. We believe it does this because the heat causes the lubricant to lose some of its thickness and make it to fifth gear. I was wondering if you could give me some pointers and possibly tell me the correct type of lubricant I should use in the transmission. Thanks and Happy New Year!

Answer
Ryan: What a wonderful Christmas gift! Whenever you get a new car to you, the best thing to do is also buy yourself a repair manual for that car. Most parts stores have them, they cost around $20.00 and are well worth the money. I would try to get a Haynes as they stick close to only a few years. Most pictures and walk you through a lot more things. In my repair manual it says for the manual transaxle lubricant type (API GL-5 SAE 75W-85W Gear lubricant). You know don't you that your clutch is hydraulic, here is some ideas from my repair manual but you will need your own to check them out... noisy in one partiaular gear; damaged or worn constant mesh gears, damaged or worn synchronizers,or it could have the wrong lubricant in it. At times this lubricant can be costly, so people will save a bit of money by using something else. That maybe worked in their Ford or Chevy so they are sure it will be just fine in their import too. Of course that is just not true. So I would change the lubricant and see if that helps. One more thing I always tell people that have got a new car to them, is do a tune up on the car. Because you have no idea how the person before you treated that car, then you should be good to go. I hope this helps and have a Happy New Year too: Linda