I'm presently overhauling my TO30's engine. The old engine had been "overhauled" by the previous owner, but the block had cracked lower webs that he welded, but which distorted them and resulted in coolant leak into the oil system. I found a replacement block with no cracks, had it prepped at the machine shop and am now about to install the sleeves. I cleaned up the lower sealing surface for the sleeve o-rings with a hone and I'd like to ensure that they don't leak any coolant into the oil. The manual says to use vaseline or light grease to lubricate the o-rings for installation, but I wonder if there is a suggested sealant that would both lubricate as well as provide additional sealing when it sets. Has anyone used something other than silicone sealant for these?