fj40 transmission fluids

[frontierjam]

i have a 1975 fj40 and im changing the fluids in the transmission and i dont know what weight of hypoy fluids to put in it... i have be recommended 80w-90w but when we flushed the transmission the oil in it seams not as thick at the 80w-90w...

 

[Hltoppr]

80-90 weight will do the trick. IIRC Toyota recommends 90 weight, but it should be no problem with a multi viscosity oil.

-H-

 

[MoGas]

80-90 unless you are in a very cold climate or a very hot one. Even then, 80-90 would work. Your mileage would suffer if you are in a very cold climate and the viscosity could break down faster in a very hot climate.

The most important thing is that you should use a GL-4 oil in transmissions. The GL-5 isn't designed for use with synchros in older transmissions.



Dave

 

[frontierjam]

thanks guys..

 

[AndrewP]

The most important thing is that you should use a GL-4 oil in transmissions. The GL-5 isn't designed for use with synchros in older transmissions.

Dave

Yet have you ever seen this to be a problem? Most if not all GL5s are properly buffered and don't harm the brass syncros. Mobil1 even used to advertise this for their 75w90. Plus, try finding a conventional GL4. I've also run cheap GL5 in my 1959 SM420 with absolutely no issues. My Toyota 4 speed has run the same cheap gear oil for at least the last 8 years and I recently replaced the bearings and converted an H42 to an H41. The syncros were perfect. My H55 is running Redline MTL (which they say meets GL4) but only because I got the tranny new and it's run synthetics since it's first mile of service.

For the OP-your tranny has been running GL5 oil for decades, because that's all that's available. Clean and fresh gear oil is better than what's in there so don't worry about it.

If you want to really use cheap gear oil, the AutoZone store brand is labeled GL5, GL4, GL3. I didn't think it was possible to meet every spec, especially a spec like GL4 that no longer exists.

 

[roscoFJ73]

If your old oil didn't seem thick enough,it was probably overdue for an oil change

 

[rusty_tlc]

If your old oil didn't seem thick enough,it was probably overdue for an oil change

Exactly.

IMHO almost any gear oil will be fine in an H42 transmission. They are designed for use in primitive environments and remote areas. Along with the venerable SM420 and SM465 they are among the most robust transmissions ever made.
I know for a fact that you can run one for over 100K miles without an oil change and it will still work just fine. After 100K miles the oil will be very thin, almost like automatic transmission fluid.

 

[cruiser guy]

For the OP-your tranny has been running GL5 oil for decades, because that's all that's available.

Not necessarily! Check out the developing world and you'll find the minimum out there. I've seen stuff that has no rating but you'll have to look hard to find the good stuff.

It's true though, the Toyota tranny will work just fine on most anything.