Tanks are manufactured by OEM's (original equipment manufacturers), not by OMS, Aqualung, Scubapro, XT, Aquaaire, etc. You need to determine which OEM tank you are talking about. The best lead you have so far is that the OMS tank was a PST. This is believable because PST was the original manufacturer of hot dipped galvanized tanks for SCUBA. This type of tank has the most reliable corrosion resistance. There are other coatings used. For example, Faber makes a tank which is spray galvanized and painted. These have fairly good corrosion resistance. Moreover, the Faber is internally coated which can reduce powder rust. The OMS tank is purchased from Faber and painted with IMRON which is nothing more than lipstick on a bare steel Scuba tank. OMS specialized in buying those Italian made tanks and tripling the price. Now, I am hearing they are searching around for an OEM which will supply them hot dipped galvanized tanks? Little wonder considering the complaints which OMS has received. The OEM, Worthington has tried to capitalize on PST's problems and fill the market gap with their own galvanized line of tanks. Sounds like a good idea to me. You need to ask OMS or an LDS as to the origin of the OMS tank and also as to the type of finish on the steel.