Dexron 3, 4, 5 etc

[stevieturbo]

A lot of manual boxes specify Dex 3 etc. Some newer versions may now specify Dex 4.

Seemingly the new versions are a better more robust oil. Is there any benefit using a newer/higher Dex number where a lower number is specified ?

[cmsapms]

Not the same numbering system, but I swapped from an API GL-4 oil in my Westfield's SC/CR Type 9 box to a GL-5. I figured a bigger number was better. I couldn't change gear!! It turns out that GL-5 is too "slippy" for the old Ford synchros to work. I replaced it with redline MTL.

Long story short, use the recommended spec unless you know the later spec will work.

[stevieturbo]

The ratings on manual oils is different. GL5 is not un upgrade or newer version, it is a different build.

In general, newer Dex numbers are all backwards compatible, just wondering if they're worth it.

[TheEnd]

Yea, it's a mystery, that one. I know they were backward compatible, but you can usually still get hold of the older versions.

Either a lot of customers refuse to accept anything else than one is on the lid, or there is a quantifiable difference.