Depends on the specific model of dryer. Maytag transitioned circa 1976 from their Halo-of-Heat design (has a circular filter mounted at back of the drum) which had drum bearings that could potentially leak some lubrication to a design (filter is at front inside the door opening) that doesn't have such bearings. A 40-yo unit should date after that change but people often mis-judge the age of their appliances. The model number will tell for sure (and the serial number is coded for the year and month of production if you want to know the age more accurately).

A photo of the suspect oil in the drum would also be helpful.

Hi dadoes. Dang! I take pics of everything everywhere, but forgot to take a pic of this oil spot. I just wiped it up immediately. It almost looked like coffee had been spilled in there, but that's not possible. It was all in the very front of the dryer. It was a tiny bit greasy, but not much and had no odor. I bought this Washer and Dryer in l980 (still have the receipt). However all the online instructions on finding the date of manufacture don't seem to apply to the serial number I have for it. Like I said, there's no unusual sounds to this dryer, except some squeaking at times. My guess it was made after the l976 date you mentioned. Nothing that was washed 2 days ago appears to have any stains on them. DH washed some work clothes in it before that and had some chain saw bar oil on his clothes, but it doesn't make sense it would come off like this in the dryer later. The spot was about 1 and 1/4" tall and maybe 2" in length. It was a small puddle that was maybe 1/32" deep. Seems like if the motor lost some oil it would have splattered all over the drum and not pooled right inside the door at the bottom of the drum. We're sort of afraid to use it now. I'll just dry old work clothes that we don't care about first.......but who knows when it will develop oil again.... I appreciate any insight you might have. Thanks!

Assuming the design (can't be sure without the model that you're keeping secret, LOL), the motor is under the drum toward the left side and more toward the back than the front. Not reasonable that oil would get into the drum from it. There are two support rollers at back of the drum but they run on oilite/impregnated bronze bearings so no oil involved that would leak (unless someone oiled them). Front of the drum rides on nylon slide-pads so no oil there. Was the residue more watery than oily? Condensation from hot/moist outdoor air blowing in through the exhaust?

Online sources for decoding appliance serial numbers may not be accurate that far back. I can probably decipher it if you cite the model and serial here.

Sorry about not giving you the model and serial numbers. I didn't think they were useful anymore. You must have special powers. :)

The Model number is LDE608 and the serial number is 516321 EC. The series number is 01.

The residue seemed like watery oil. I too was wondering about the high humidity we've had recently.......but yesterday that humidity finally dropped. I had just cleaned out the outside filter. Could it have anything to do with the possible buildup of lint from the dryer to the outside filter, on top of the recent high humidity? It's all very strange. I couldn't believe my eyes when I saw it. Just weird. We live in the country and I had a fleeting thought that maybe a mouse peed in there, but I don't think that's possible. haha Like I said, we hadn't used the dryer for a day and a half, and there were no signs of oil on the light colored towels I dried last. I appreciate your help here dadoes! We might never figure it out, but it sure makes drying important things now a little scary.

Manufactured Feb 1980. I have no further suggestions on the residue. Perhaps leave the door ajar for ventilation when not in-use? ... unless there's a drum light that would stay on.

Thanks for you help dadoes! I appreciated it.