brunson67

I'm going to change the gear oil in the trans of my 1992 4Runner 5 Speed trans. I've read that I need to use GL-4 75W-90 (3.5 quarts). It seems that Redline is the preferred brand, which I cant find anywhere locally. I have found other brands, but they all say GL-4 and GL-5 compatible. I'm assuming I need to stay clear of these and use straight GL-4, correct?

Also, there is a sensor on the passenger side of the trans that appears to be leaking, it looks as though it is threaded into the housing, I believe it is a reverse switch, does this sound correct? And if so, is it just NPT threads? Do I just un-screw it and clean everything and use some pipe thread compound and screw it back in?

Regarding actually draining the gear oil, I had read somewhere to make sure to remove the fill plug first, is this just to help with air so the fluid will drain?

Thanks,

Newbie Rob

scope103

The GL-5 specification is for higher loads and higher speeds than the lesser GL-4 classification. https://en.wikipedia.org/wiki/Gear_oil Like any specification, they are "minimums," so an oil that is GL-4 "compatible" meets the specification. Why do you care that it would also work in a higher load situation? (For that matter, why would anyone bother selling a gear oil that only met the lesser classification, when a dual classification oil costs no more?)

Personally, I've never been that impressed with "designer" oils. They all come from petroleum. But if you have reason to like Redline, go for it.

There are no NPT threads on your Toyota (a few BSPT, but that's a different story). IF you have an R150F (it's printed on the door pillar), here's the manual page: http://web.archive.org/web/201107082...18componen.pdf There are lots of things that attach to side of the transmission (backup light switch, restrict pin, speedometer driven gear), but according to the drawing they all have seals. So are almost certainly straight thread (and pay attention to the torque values!) And you'll need new seals, e.g. https://parts.lakelandtoyota.com/pro...m=90430-18008; teflon tape will do you no good at all.)

The fill and drain plug haven't been removed from your transmission for the past 15 years (maybe longer). What if, lying in your driveway, you just can't get one out? Wouldn't you like to find out that you can't remove the fill plug BEFORE you drain out all the fluid? (You still have a problem, but at least you can drive it somewhere.) That's why (so far as I know) you remove the fill plug first.

snippits

My 92 pickup has a W55, and it specs 75W/90 or 80W/90 GL-4.

NAPA stocks and sells Sta-Lube 85W/90 GL-4. I used it for a couple years. Drained it, and now I am using Redline MT-90. Don't really notice any difference between the two except for really cold mornings, and then by the time I drive 1/2 mile or less no noticeable difference.

You can wait for the NAPA 10% discount to show up, and get a gallon for about $34. The 10% online discount pick up at the store happens lots.

https://www.napaonline.com/en/p/SLRSL24239

75w90mantraN

I dont drive a 92, but my experience is the same - doesn't matter the brand. Just dont save leftovers on the shelf like me before. Moisture builds up and it wreaks havoc on functionality. Whats important is filling to the correct level. You definitely feel the difference if its off.

Used to do the redline. Great stuff. But Chevron's Delo is just as good in my diffs and tranny and more accessible where I live.

cbh148

Lots of people have run GL5 with no problem in Japanese manual transmissions that are manufacturer-spec'd for GL4, including myself in my 240sx (out of laziness, plus 350whp means that car needs a beefier trans adapted sooner or later anyway). I still elect to play it safe and seek out some GL4 just in case, because if GL5 really is bad for the transmission like lots of people say it is, then the alternative to spending a little more money on the gear oil is screwing a transmission that presumably was in good condition with no grinds before the oil change. Not worth the risk to me. Driving a stickshift that has a gear that grinds just plain sucks.

gsp4life

The 1st time I changed gear oil I used redline because the internet said it was the best, but have since switched to the cheaper sta-lube 85w90. Even on the coldest days (5-10°F), it shifts fine after a short warm-up. I'll keep using sta-lube from here on out.

RJR

As scope103 says, your manual specs either GL-4 or GL-5 for the tranny and tcase, GL-5 only for the differentials. GL-5 was originally formulated for differentials when automobile manufacturers went to hypoid gears back in the mid/late 50's to lower the driveline tunnel. Hypoid gears are kind of a combination between a straight right angle drive and a worm drive. As such, there is a lot of sliding of one tooth over the other (in a pure right angle gear, the teeth roll over each other and do not slide), requiring a gear oil that can handle the sliding action as well as the high tooth pressures involved in a diff.

The additives originally used for GL-5 (sulfur compounds, I think) had the side effect of attacking the brass metals used in the transmission synchronizers, so GL-5 gained the reputation of not being good for transmission use. Over the years, GL-5 recipes have changed such that this is no longer a problem with modern gear oils, but the "conventional wisdom" remains.

So, as per Toyota, GL-4 or GL-5 are both OK in the tranny. ONLY GL-5 should be used in the diffs, however.

brunson67

Thanks for all the input. Reason I asked was I've come across a few topics and the GL4 was recommended for the R150F, helped with the synchros, and all of the 75W-90 gear oil I've come across at the parts stores is a GL4-GL5 blend. My OG manual specifies GL 4 for the transmission and GL5 for the diffs and I believe the transfer case. But if the this newer type of gear oil is fine I'll just drain it and refill with it. It is currently shifting a little hard, but it could be just low on gear oil I'm thinking.

RJR

I should have pointed out that, because GL-5 is "slicker" than GL-4, people still find that sometimes GL-4 will improve synchro operation in a worn transmission. The GL-5 won't damage the synchros, but it can make them work less effectively.

brunson67

Thanks RJR!

ev13wt

You pull the fill plug first, because what if you screw the fill plug up? Ya can't fill from the bottom hole (IF you do, and the oil is out, fill from the top after pulling the lever, but not for differentials)
Correct level is (make sure the trucks treansmission is "flat", not on an incline or a jacked up rear (rake). Fill GL4 of any brand until it flows out of the hole. It's not rocket science and it's just a truck with 100 HP.

The plug is probably reverse. No pressure in there, so it's a standard metric fitting. Some goop or your compound will do nicely.

snippits

When I changed the fluid in my 92 2wd W55 trans and rear end, I bought a 10 pack of Toyota drain plug crush gaskets. Worked for both trans and rear end. The rear end was already seeping a little bit, so it needed a new crush washer.

I paid $12 for the 10 pack in 2017.