If they are old, you might consider some new bearings. Dads ol' tackle has bearing kits, and individual bearings to get them working tip top. Throw away any oil that is thick. If you have questions throw them out. Youtube is your friend.
Prosise
By the way, In my opinion and everybody has one.. This oil is the best I have run across. Was talking to one of the guys at Dadsoletackle when I was rebuilding a couple of reels about 4 yrs ago. Ask his opinion, and he said their synthetic oil was really good, and cheap.. I just touch the tip to the bearings, and let it wick into the bearing. Magical stuff. Im using exposed hybrid bearings so they are easy to clean. Sealed are a bit harder, i soak the bearings that have sides in 100% ipa. Has to be 100% ipa for the Bernoulli affect to dry completely. Hit it with some low pressure compressed air, and allow to dry fully. Some air compressors will actually introduce moisture so allow ro dry in the sun. One drop of oil, and manually turn the bearing with some form of redneck contraption.. if you feel anything rough, its time to replace. Most standard bearings (sealed) are cheap. It gets expensive in ceramic, ceramic hybrid, or abec 7 and above but it will make a reel work very well.
Here is the link to their oil
Dads ole tackle oil 7$