Alright, my requests on Minecraft Forum and the private FTB support site I have not gotten an answer to this question. The problem is that my FTB instance lags out so bad when I near a large (almost taking up an entire chunk, based on my guess) Buildcraft oil spawn. I generally last about three minutes before the console starts outputting memory errors and the game lag bombs so bad you have to kill it with Task Manager. Here's a log of what occurs on the console. I've removed the chunk loader I placed in the area and it should also be noted that I am playing using the Direwolf20 map available in the launcher. Other maps work fine using the same pack. What can I do to prevent this?
If you take a look at the bottom of the log file, you can notice that the game is having continuous rendering errors, most likely caused by the oil. Rendering this oil is using up a lot of memory, and even making the game run out of memory, as you can see is happening in your log, at this line: (and a few lines below this)
Try turning off the liquid animations, and possibly lower other graphics settings. If this still doesn't work, the best thing to do is to contact the mod developers at the FTB support site. This lets the developers know so that they can fix the error.