Reply To: Mid 50’s gear lube

[Bob Wight]

I did some research on this subject some time ago. A google search on the topic of “yellow metal safe” will reveal a variety of opinions, theories and alleged discussions with various oil company technicians on the subject. Most of these discussions opine that a GL-4 rated oil is probably a safer bet to use to protect bronze or brass components. CRC Sta-Lube still offers a GL-4 rated oil and it does specifically state that it is not corrosive to bronze, brass or copper components.

https://www.crcindustries.com/products/api-gl-4-multi-purpose-gear-oil-85w90-32-fl-oz-SL24229.html

Many other discussions indicate that the sulfur additives initially used in some GL-5 oils were found to be harmful to brass and bronze, manufacturers changed their composition to inactive sulfur to avoid such damage. But what do I know, I’m no chemist. I’m with Tubs, I’ll just run them.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
1982 Evinrude 25hp

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."