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Manual Transmission oil

24525 Views 34 Replies 12 Participants Last post by  hitek14
Hi I have a 1965 mustang with an original Ford 4 speed. I want to change the transmission oil, but I don't know which oil I should use.
Also, I daily drive it pretty much every day, not really in the winters but I will need an oil that can operate at lower temperatures (Nothing crazy, like I use 10w-30 and it works fine. I live in SLC, UT if anyone is familiar) But I have noticed that when I change gears in the morning (fairly cold), it shifts hard. But then warms up and functions better. So i know that is normal, but i am debating about switching to a lower viscosity. Anyways, I would love to hear any input! THANKS!!
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As has been said, Ford specs out GL-4 for the toploader and it is better suited to the blocking rings than the current GL-5 lube. GL-5 will not make the tranny "blow up", but if it's available, get the GL-4.

I bought mine from amazon when I was ordering some other stuff. IIRC, it was only $22 at the time.
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