My 3.03 three-speed toploader is gettin’ a bit noisy. Think I’ll start with a gear oil change, even though there may be a rebuild in my future.
The Shop Manual specifies quantity but not type (as far as I can find.)
I’ve searched the forums and around the web but didn’t find too much on the matter there, either. Seems to come down to 75W-90 or 80W-140 (heavy usage or hot climates), and the toploader rebuilder sites seem to prefer conventional versus synthetic because it works consistently no matter the type of driving.
Being a desert dweller, I’m leaning toward 80W-140 and finding products by the usual companies: AMSOil, Lucas, Mobil, Valvoline, etc.
I use whatever is cheapest! Run Walmart oils all the time with good results, both engine and transmission oils. WM buys from one of the major oil suppliers, mainly Exxon-Mobil and Warren Performance Products from what I understand. www.bobistheoilguy.com
I think the most important part of changing the Trans fluid is to be absolutely sure to use GL-4 spec fluid. Stay away from GL-5, or ones that say “meets GL-4 and GL-5 specs”, or words to that effect.
The GL-5 fluids are known to cause issues with the brass components that were used in our vintage transmissions, and can cause shifting difficulties.
At least that is my understanding of it all. And don’t worry, GL-4 was still on the auto store shelves when I did mine earlier this year.
Thanks, Mike, I’d forgotten about the GL-4 / GL-5 thing. As it turns out, this is more difficult than I expected. I researched a lot more brands than shown below, but it seems to come down to GL-4 is only available in the lower range or high single viscosities:
All of the 85W-140s are either GL-5 or synthetic or both. I’m seriously tempted by the AMS Oil product, but want to use a conventional formulation. Citgo doesn’t seem to be easily available in my area so I’m going to try the CRC Sta-Lube API/GL-4 Multi-purpose Gear Oil in 80W-90 weight, which my local NAPA has in stock.
FWIW, I remembered to dig out my 1968 Passenger Car Maintenance and Lubrication Manual. For manual shift transmissions, it specifies Ford Standard Transmission Fluid (C3RZ-19C547-B, Ford spec. ESW-M2C83-B). These days, of course, those numbers are all meaningless.
