I have an old light weight 10x gore tex rain suit, and a newer mid weight coat with built in hood that I have worn in the rain some and it has done well, but its not a rain coat. I want the insulation factor for an upcoming trip to Alaska, but dont want to spend the money for a good rain suit that I wont use when i get back. Anyone know of anything good to put on that coat (or the 10x rain suit) to improve the water shedding abilities? Here, if its raining that hard, I just go in but up there I may have to.

They sell stuff at academy to water proof tents that would probably work. Not sure of the name it is in the camping section. Probably get the same kind of stuff at Walmart

There are several made by Nikwax sold at REI and Bass Pro sells one called ReviveX. They're both made specifically for waterproofing clothing. After you spray it the garment has to sit for 24-48 hours to completely dry and cure.

Thanks everyone, after spending an hour or more on the internet understanding why my old gortex rainsuit wasnt doing the job, I went to REI and discussed the options and they recommended Techtron dwr water repellent over the Nikwax pump spray, saying they would both do, but this cost less. He says the seams may still leak since its not a high quality rainsuit but should do for my needs. I really learned a lot this afternoon about rainsuits.

That's one of those things not many people think about until you need it.

If it is GoreTex, a simple washing with a mild detergent and double rinse may solve your problem. Any & all goretex products will leak if it is dirty, even the very best quality rain suits. The dirt fills the pores of the goretex material and allows water to go through.