I have two issues with a '97 cabrio that I just purchased for my teenage daughter. 1. There is a small leak of oil looking substance. After 1 day it was maybe the size of a silver dollar. It appears to be coming from the backside of the transaxle where it meets the oil pan. 2. Also, I made the mistake of not test driving large distance in reverse. After getting it home, when backing out of driveway, I noticed a strange sound. The car has a manual transmission and only makes this sound while the wheels are turning and in reverse. Does not make the sound rolling backwards in neutral.

Most reverse gears on manual transmissions are square cut which makes them whine when engaged, all forward gears are helically cut and are therefore silent in comparison. Do you think the noise you experience is down to gear whine? The drop of oil could be a partly worn half shaft oil seal. Oil seals tend to be a bit stiff when cold and occasionally but after warming up they resume flexibility and become oil tight. Determine that it is in fact gear oil and not engine oil running down the back of the engine from the PCV or head gasket. Determine that the respective oil levels are where they should be on the dip sticks. Monitoring the oil consumption/loss on the dip stick is the critical thing to do over the longer term. If the loss of oil, between 10,000 service intervals, is low, say about half a pint, this will be not even enough to take it to the MINIMUM on the oil stick. When you change the oil put in enough to take it to the MAXIMUM level. Often it is much cheaper to overlook very minor oil loss rather than face the cost, effort and disruption to have a cylinder head gasket replaced.