When I had my Toyota that called for T-IV, I looked into my options for replacement, and learned something about the WS spec in the process. The two are not interchangeable, though an early version of a given transmission may have used T-IV, and a later version, WS, there is speculation that different clutch materials are used.
I learned XOM manufactures the bulk of T-IV, and WS, at least for North America, if not most of the world as well. They are also known by two other spec codes. T-IV = JWS3309, and WS=JWS3324. I've had a few fluid changes on the Toyota where it was similar to dealer cost, but definitely more convenient to grab XOM branded JWS3309 from a nearby store. Don't think I've ever seen JWS3324 in the wild, either.
These fluids may not be synthetic, or by any means particularly spectacular, but I have never heard of them being problematic in any application (unlike say Honda Z1 ATF). Sure, other fluids might work, they might have better specs, and might be synthetic. Cost of the OEM stuff isn't particularly high (unlike say some ATFs for ZF trannies). So am I actually achieving anything by straying from spec? I didn't think so, so there was no incentive to switch for me.
Where you might find other sources of WS and T-IV, are from the dealers of other makes (though my experience is Toyota seemed to be the best price), that use Aisin transmissions. (Hmm, didn't we see someone talk about Aisin ATF? I wouldn't hesitate to use it, considering they made the transmissions).
Automakers that have used Aisin trannies are quite extensive, and probably almost all automakers have had them in their vehicles at some point or other.
I learned XOM manufactures the bulk of T-IV, and WS, at least for North America, if not most of the world as well. They are also known by two other spec codes. T-IV = JWS3309, and WS=JWS3324. I've had a few fluid changes on the Toyota where it was similar to dealer cost, but definitely more convenient to grab XOM branded JWS3309 from a nearby store. Don't think I've ever seen JWS3324 in the wild, either.
These fluids may not be synthetic, or by any means particularly spectacular, but I have never heard of them being problematic in any application (unlike say Honda Z1 ATF). Sure, other fluids might work, they might have better specs, and might be synthetic. Cost of the OEM stuff isn't particularly high (unlike say some ATFs for ZF trannies). So am I actually achieving anything by straying from spec? I didn't think so, so there was no incentive to switch for me.
Where you might find other sources of WS and T-IV, are from the dealers of other makes (though my experience is Toyota seemed to be the best price), that use Aisin transmissions. (Hmm, didn't we see someone talk about Aisin ATF? I wouldn't hesitate to use it, considering they made the transmissions).
Automakers that have used Aisin trannies are quite extensive, and probably almost all automakers have had them in their vehicles at some point or other.
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