This part is in reference to the machine oil taste on Kanger Subtank OCC heads. I have never had this issue with genuine coil heads. I have however had this issue with non-genuine coil heads. Counter fitting in China is legal and is rampant and many vendors here purposely buy the cheaper ones to maximize their profits or they simply bought from a Chinese vendor who lied to them, which is common no matter where you live. I've purchased the cheap non-genuine ones off of Angelcigs and Fasttech, their about a dollar a piece but they are by all means inferior to genuine coils but in their defense, they made no attempts to label them as authentic. I knew I was buying non-genuine coils and I wanted to see how they stacked up. Their Ohm's are all over the place, the coil leads need to be trimmed and they certainly need to be cleaned. However non of those issues make them useless, they just need a little extra attention before use. My preferred place to buy genuine Subtank coils and all other Subtank parts is Sweet-Vapes.
As for which is the better tank, Delta II vs Subtank Plus/Mini/Nano or anything else currently on the market, it's all going to come down to personal preference, as with most vaping devices. The Subtank series has one flaw and that is the RBA head, which there are apparently close to six different iterations of. These variations come through with how the channels were drilled and what sort of insulator was used. Yes it's is a bit frustrating on one side but on the other side Kanger has taken great steps to improve the issues and will send you new insulators if you mail them. It's a bit of a hassle but it's also a good sign of faith to its customers from Kanger, which is awesome!
I will say, that I have never tried the Delta II, it's a nice looking tank but it's to highly priced and so are the coils for it and so are the replacement parts for it, if you can find them, unlike the Kanger Subtank's who's parts are readily available, fairly priced and easily found. There are also a few things about the Delta II that turn me off, for the price, no copper should be being used, period, that is a slap in the face to us. The ceramic "stuff" in the coils is also a huge red flag, don't ever use any coil with ceramic material in it, it isn't safe and that has been proven. Which is also why Aspire has/is moving away from ceramic/whatever materials. The Delta II looks really nice but it would have been nicer if the windows were a little larger and I have read that people do have a hard time seeing the juice level and I have heard that it is a little more of a pain to fill than other tanks.
If you own a Delta II and love it, then great for you and I would recommend only ever using the RBA head from now on. If your thinking of buying one, I wouldn't recommend it, purely based on the ceramic material in the coils, it isn't safe, not to mention their made of copper and are ridiculously over priced. Especially when we have so many sub ohm tanks on the market now who don't use cheaper or ceramic materials.
I probably have close to thirty different tanks, from Kayfun's to Nautilus's, Aerotank's, LEMO/MELO's, Atlantis's 1 and 2, including the Subtank Plus (V2), Subtank Nano and Subtank Mini. I'm not trying to brag but the point is, 99% of the time, you will see me only using one tank and that is the Kanger Subtank Mini, I actually own four of them because it is so awesome. It really is such an amazing tank, it has great airflow, five different colorways of o-rings for customization, cheaply replaceable glass, Fasttech even offers different colored glass. It's build quality is fantastic, there is nothing cheap or questionable about it. It simply is the best tank I own and I probably wont buy anymore non-Kanger Subtanks, ever. This is exactly what I have been looking for in my year and a half of vaping and now that I have found it, there is simply no need to keep looking.
I would also like to state the MELO is also an awesome tank to consider, the coils are awesome and at $20-22 per MELO and $10-12 for a set of five coils for the budget minded Sub-Ohm'er, you really can't go with the MELO. The Atlantis 1 and 2 are also awesome tanks. They are all really great tanks and all completely 100% compatible with one another. So if you want the MELO flat top on an Atlantis 2 air flow control valve, go for it. I also think the cheaper MELO coils work better than the Atlantis V1 and V2 coils. Then especially if you add an Anyvape Segatank RBA head to it, which will also work with the MELO and both versions of the Atlantis, you will be golden. DiscountVapers sells them $5.95.
Even with all of that, if I could recommend one tank to rule them all, it's hands down the Kanger Subtank Mini, considering you get one with a newer RBA head and if you do get or have a bad one, you can pick up the newest and best one from Sweet-Vapes for $7.95 while you wait for Kanger to send you a new insulator free of charge.
I would personally never encourage anyone to pick up a Delta II, it has questionable materials, poor customer reputation, potentially unsafe coils and cheaply made overpriced components. I would however and do recommend the Kanger Subtank Mini to everyone. The Nano and Plus versions are also equally great but for me, a guy with most of my mods at 22mm, the Kanger Subtank Mini looks amazing, no matter what I throw it on.
Every product and company has it's flaws too, nothing or no one is free from flaw but that fact that Kanger is taking a very proactive step to fix the RBA heads at no cost to you speaks volumes about them and I will continue to support and do business with any company who takes care of and values it's customers!
As far as I am concerned, the absolute best possible vaping experience as of 4/20/2015 includes a Kanger Subtank Mini, a temperature sensing mod like the DNA40, using Ni200 coils and some tasty juice, that combo spells game over for any other possible scenario. Anything else is just overkill and unsafe and I don't care if you have a 500watt mod with eight coils in it that can drain 10ml of juice in one puff, lol.