2004 Frontier 2.4 Automatic

[04Frontier2.4]

When I first started driving my 04 frontier, the transmission seemed to shift ok and smoothly except for when it got cold outside and the engine was cold. It would feel like it wanted to slip a little bit from 1st into 2nd. I checked the fluid and it was a couple quarts low. Now I know that with Nissan and Honda the fluid matters what kind you use... But I called the parts store my shop deals with and one older guy down there that knows his stuff recommended a couple quarts of Valvoline Max Life "Multi-vehicle" DEX/MERC fluid. It says on the on the back it's compatible with "Nissan Matic-K" fluid. Being that It's my vehicle and I got the truck for free needing some work to the engine... I didn't want to spend too much money from Nissan and I wanted the fluid now so I got 2 quarts but I ended up not really needing the full 2 quarts. But since the adding of the fluid when I start off driving and it shifts from 1st into 2nd it does it hit. You definitely feel it to where the truck kinda jerks from it and depending on how hard you are on the gas depends on how hard it hits. Sometimes it doesn't do it at all. It doesn't do it in any other shift change into any other gear. All other gears are very smooth when it shifts. So smooth you cant feel it. Now I don't think that even if I used the wrong type of fluid that less than 2 quarts would make that dramatic of a difference. If it were a CVT then yeah I wouldn't put anything in other than recommended Nissan type but at least I used a type compatible with Matic-K. Any suggestions on what could be happening? Did I mess up bad putting in the wrong type? I had a transmission shop down the road test drive it and they couldn't really say what was going on or that it was even a concern. Only thing they could recommend is a rebuild at 1400 bucks. The owner of the transmission shop is friends with the owner of my shop. We just don't do transmissions at where I am. We send all our customers with transmission issues down to him so hes not really trying to make money off me. I know that if they cant tell me the issue, then no one here can either accurately. But... Does anyone know of a additive that I could add that is compatible with Nissans and could possibly fix this hard shift issue?

[butterman2473]

I also drive a 2004 2.4 w/ automatic. Owners manual states that Matic D is the recommended ATF. I personally have switched to Royal Purple full synthetic. Approximately 5 month's ago I purchased 12 qts and drain and filled 3 times with about 15 minute drives in between. Mine also shifts hard into 2nd. It'll give that 2nd gear chirp of the rt. rear tire if I'm romping on it. I remember reading somewhere(probably at Clubfrontier) that it was engineered that way to kind of compensate for the lack of power....so to speak. I'm not fan of additives. I kind of look at additives as a last resort type of thing.