What if I switch to Royal purple Synthetic ATF for my tranny?
 

What if I switch my tranny fluid to Royal purple Synthetic ATF. I have an auto. You guys know I've been experiencing problems with the tranny. Where the shifts are too soft and that my cousin messed it up. I've been told if the tranny has problems and switching fluids might make it worse.

Right now I'm using oem fluid called Matic D from nissan.

Also my mpg dropped from 28 and some change to low 27. That is per tank mpg.

What do you guys think?

It's difficult to say if
 

It's difficult to say if changing fluids would fix the problem without knowing what it is. I've had transmissions I've switched to synthetics that shifted and performed better but they where working well to start with. Temps drop and they shifted smoother. Draining and filling with RP or another synthetic is expensive gamble to maybe fix the problem. You might want to solicite advice from a local transmission shop,or dealer? I'm not sure if it would apply to Nissans, but with old th350's and c6's and the like (old std us autos) we'd run racing transmission fluid from B&M or simular. It firmed up the shifts and cut down/eliminated slipping. We did it for performance and racing but I would think less slipping would aid mileage as well.

I had the unit that controls
 

I had the unit that controls the transmission checked and there was no codes and it said everything is working, it's not the ecu, that is different.

I really feel the transmission slipping, I even have to press the gas more to get it to move. When I put the pedal to the metal the car accelarates significantly slower. My mpg went down by like 1.5mpg. I checked the tranny fluid and it still looks new. I had a tranny cooler on this car since 2004. The problem started last year when my cousin downshifted while driving on the freeway and put it in N while on the freeway then back to D. Last time fluid was changed was 12000 miles ago.

slipping
 

Keep in mind that the filter in the tranny is probably doing its job and removing all the stuff that would dirty the oil. I think the automatics use hydralic pressure to release the clutches and springs to make them grab. That is how it gets locked up in park - no pressure all the clutches grab. If your clutches and bands are worn then they need to be adjusted tighter to properly grab - I think it is a simple adjustment once you take the bottom pan off. Changing the oil in a transmission that does not work properly is not going to help it any. Checking the filter may show some debre and it should be cleaned.

Check this site out.

https://www.familycar.com/transmission.htm

We will see how taking out
 

We will see how taking out the fluid helped or not in the next tank. If I'm back in the 28mpg range then it's all good. If it's 27mpg then I got problems.

Give it at least a few
 

Give it at least a few tanks. My mpg fluxuates 2-3 mpg every tank not changing anything.

JanGeo
 

Front Wheel Drive Automatics use a separate lock-pin/gear that stabilizes the vehicle in park. Nothing engages when the vehicle is in park as all the fluid valve bodys are depresurized. The drive axles & Diffential gears simply rest upon the lock-pin/gear assembly that the valve body engages as it gets shifted into park.

Also, the clutches grab ONLY under pressure. Clutches and Bands CANNOT be adjusted on a front wheel drive. Only on the old school rear wheel drives. And, Never simply clean a transmission filter. Always replace. (make sure you get a rubber gasket too, stay far away from them corks :P)

tranny
 

Seems my knowledge is dated - I stand corrected - thanks! After reading the article it also says everything is operated by oil pressure - clutches seem more complicated than I imagined also.

ok, I'll see it over a
 

ok, I'll see it over a couple of tanks.

shifting at highway speed
 

I asked my brother about shifting into neutral at highway speeds and then back into drive - he frowned for a few seconds and then said that should not bother the transmission as long as the engine was still running.

Maybe your cousin got a little reverse? before he found neutral...he said the changing of the oil might help but not likely.