For clutch bearings I have been using the same sets for gallons and gallons (upwards of 15 gallons or more) This process started by accident but it has worked for me. Here it goes...
supplies needed, 1 pint or quart of Marvel mystery oil, 2 sealable containers (I use old film canisters), motor spray.
I have three sets of clutch bell bearings. 1 set in the buggy (pair 1), 1 set in oil in my pit bin (pair 2) and one set in oil at home (pair 3).
After a day of racing, I take out the set that are in my buggy clean them with motor spray and put them in the container at home (pair 1 has now become pair 3). I then take the container thats in my parts bin and pull out the bearings let them drain on a towel for a little bit of time to get all the excess oil out so it doesn't foul my clutch (pair 2 has now become pair 1). These go in my clutch for the next race day. The pair that are at home then go into my tool bin. (pair 3 has now become pair 2). If you race every weekend, each pair of clutch bearings gets 2 weeks off and 1 week on. But in case of a failure you have a set that has been in oil for almost 2 weeks.