There could be several factors involved in what you described. It could have been a result of a dull chain, improperly sharpened chain, uneven sides of the bar's rails, the bar's gauge too wide due to a wrong gauge chain or wear on the bar, lack of lubrication on the sprocket (grease) causing friction (heat), lack of oil, or a combination of these. If you had only taken three cuts as you mention I would tend to believe that the bar already had issues, untrue, before your first cut.
When cutting larger rounds or if I am noodling I pay extra attention to the build up of sawdust and/or shavings around the clutch and under the clutch cover. This can prevent oil from doing its job.
Longer bars have more surface area for the chain to make contact with. They need more oil and the pump needs to be adjusted accordingly.
This is my first experience with TSC (Grand Opening). 6 months ago we didn't have any TSC stores in Utah, now we have 4. I have yet to use any of the bar oil that I brought home with me so I'm not qualified to review it yet. I have never had issues with the Wal-Mart flavor. Currently I am using the stuff that pours out of an orange bottle. I found and bought a bunch of it at a freight claim store for under $6 a gallon. Maybe I should sell it on here and double my money. It would still sell for less than what the Stihl dealers are asking for it. I like the Stihl oil, I like the Husqvarna oil, I also like cash in my wallet.