i just got some put in my mates gsr not to long ago...
they costed me $10 brand new n i got 16 of them to replace them all.. my work installed them for i think it was $200-$260 n the noise is no longer their AT ALL... it wont matter what oil u use, they wont shut up till u replace them...
just thought i would let ya know cause i thought that was fairly cheap... its a big job to do as well...