Leaderboard

I've done 15,000km on my reconditioned transmission using ATF dex III and had no issues. The gent who recommended it has been building these gearboxes for decades. I dismissed this at first and put 80w90 in it, then 75W/90, and couldn't select gears when cold. Now it shifts great.

Sounds like your temps are close to what I experience. I don't drive my WD21 in the winter anymore because the salt killed my last one, but I drive a first gen Xterra with the same transmission. Sometimes I have to let it idle for 5-10 minutes just so the clutch fluid warms up from ambient engine heat, and the pedal isn't a marshmallow!

The 170F (76.5C) is what they all came with originally. I personally found that one a little too cold here in Ontario Canada during the winter time. Basically, it could barely keep the window de-iced and my feet warm when the temps dipped below -15C, especially on the extreme wind chill days. In doing some testing, I found the coolant temp barely stayed at 170F once it opened when driving in stop and go traffic, because these older style ones just tend to stay open unless it goes way cold, a temp solution was covering the rad with cardboard to block some airflow. You can test the t-stat in a pot of hot water. I swapped over to a 180F (82c) when doing my water pump and it made a decent difference, imo this is what they should have put in at the factory, the later VG33E (not supercharged) in the Xterra came with that one... The 192F (89C) was never a factory option and has only been available for the last few years. I don't know anyone that has tried it, though. It's still well within the normal operating temp so I don't see it being a big issue. These trucks aren't exactly known for overheating in my experience, so it should not be a problem provided your cooling system has been well maintained and the rad isn't full of scale. In 20+ years of owning a few of these trucks, the only time I had issues running warm were with a radiator that was full of mud. My 2.0 VW motor has a 190C stat originally, that thing has the best heat out of all of our cars!

I tried to pick up a gallon of Hy-gard yesterday and John Deere shop was closed. I'll get some tomorrow. I'm planning to try it my own commuter car, a 2000 Toyota Echo 5spd, before my son tries it in his first and only rig. Both vehicles have around 300K miles I'll update this thread with what we learn.

Following this, because I remember one of my shifts being grindy, but can't remember which one...also used MT-90, and thought I over-filled it but it's been so long I can't remember!

For coolant to leave from the top of the rad, it would have to enter from the bottom of the rad. If the tstat is closed, the lower rad hose is blocked, so suction at the top of the rad would have no effect. Like you're sucking on a straw with the end blocked. If the tstat is open, the pump is sucking coolant through that bottom hose. So now there's someone else sucking on the other end of the straw, and they're better at it, and man that got weird fast. So there's either a deadhead or suction at the bottom of the rad, and an unrestricted supply of coolant coming out of the engine at the top. The datalog could be interesting, but leave the two-wire sensor alone and use the one-wire sensor for the dash (with the wire to the dash unplugged) instead. Two circuits trying to check resistance across one sensor could end badly, or at least give weird and unreliable data. And yeah, at this rate I'm gonna end up with a full backup of Nico's service manual collection on my hard drive. Sometimes it's worth it, though--last night I stumbled on the "body sonic system" in the '84 ZX manual. Looks like it had kickers in the seats, hooked to the radio. Butt subs. Oh, and RE convection. Some early cars and tractors did not have water pumps, and relied entirely on thermosiphon cooling. Heat rises in the block, cold falls in the radiator, coolant circulates. It even kinda works, mostly.