Hello,

I think I may have screwed up my transmission and I'm looking for some info to prove or disprove that thought.

First of all I installed a new radiator recently and forgot to replace the amount of tranny oil left in the old one. After about 60km of driving on the highway it started to slip in overdrive with the engine revving higher and the speed dropping. I pulled over and checked the tranny oil and noticed it was in the cold section on the dipstick even though the oil was hot and I think it may have had a burned smell to it.

Next I went to Canadian Tire and got a blended bottle of ATF that say's it works for Matic D among others. I put about half of a litre/quart in but due to the fact that it goes down the filler tube I couldn't check the dipstick to confirm it was at the right level.

The next day I checked it again and it was still a bit low so I put the other half of the bottle in. When I checked it later it was now above the top of the hot area (when hot). I had planned on draining some out tonight but as I was driving today it started to slip in overdrive again on the highway. I took a side road home with the overdrive switch off and the transmission is functioning as normal.

So now I'm wondering if I cooked the transmission from running it about 3/4 of a litre low. Does that seem possible? Also I'm thinking of getting it flushed as a last ditch effort to see if it is slipping as a result of the oil being overheated.

Some other info: 2002 Xterra SE 3.3, truck has 215,000km/133,000mi, no tow hitch, stock tires, pretty easy life as far as I know, I've owned it since 138,000km/85,000mi also I changed the tranny fluid 30,000km/18,000 miles ago.

Any info is much appreciated,

Thanks

Welcome aboard, Ben!

My understanding of the Nissan truck auto trans issues is this:

When the combination radiator/trans cooler fails, the coolant mixes with the ATF and it doesn;t take long for the trans to suffer permanent damage. You MAY have dodged a bullet, but it's unlikely. I'd drain the ATF and refill with the proper fluid, then test. If it still acts up, there's your answer.

Once you repair the trans, bypassing the radiator cooler is the way to go. You can run an aftermarket trans cooler ($60-70 from B&M) and that should resolve any future issues.

Ok sweet thanks man. Just out of curiosity do you think I should get it flushed or just drain it?

I'd simply drain and refill. No sense throwing good money after bad, in case it's cooked.

Keep us posted?

Did you ever find out the cause of this? I'm having the same problem in my 06 X. I check the fluids and they arent mixed or burnt. I feel like its some type of electrical problem. Any thoughts?