shallowwatersailor 3,213 #1 Posted August 12, 2014 With my recent foray into walk-behind Gravely tractors, I have discovered that the main gear is bronze and a number of the attachments also use bronze gears. Most manufacturers's GL-5 is death to yellow metal! The tractors use motor oil so it is not a problem (unless there are some that I am not aware would be an issue.) I believe that it has something to do with the increased sulfur content of the GL-5. Do any Wheel Horse tractors use bronze in the transmissions that we need to be aware of? Anyone know who still markets GL-3 or GL-4? Amsoil has a 5W-30 Gear Oil that is okay with yellow metal but that is not the same. Or is it? Share this post Link to post Share on other sites
KATO 115 #2 Posted August 14, 2014 (edited) Yellow metal is brass or brass containing metals. AMSOIL also makes 75W90 manual Transmission oil that is good with brass. Here's a link to the page... PDF data sheet links are there beside the picture for download. http://www.amsoil.com/shop/by-product/transmission-fluid/manual/manual-transmission-and-transaxle-gear-lube-75w-90/?code=MTGQT-EA Edited August 14, 2014 by KATO Share this post Link to post Share on other sites
specialwheelhorse 174 #3 Posted August 14, 2014 Its my understanding that gear oil for lower units for outboards Are all good with yellow since many have bronze in them. Share this post Link to post Share on other sites
shallowwatersailor 3,213 #4 Posted August 14, 2014 Yellow metal is brass or brass containing metals. AMSOIL also makes 75W90 manual Transmission oil that is good with brass. Here's a link to the page... PDF data sheet links are there beside the picture for download. http://www.amsoil.com/shop/by-product/transmission-fluid/manual/manual-transmission-and-transaxle-gear-lube-75w-90/?code=MTGQT-EA In the data it mentions "protects brass synchronizers," so I think that this might work. Bronze is primarily made from copper. Thanks! 1 Share this post Link to post Share on other sites