Gear Lube Question

Can Automotive grade gear lube {Valvoline 80 90w} be safely used on a Johnson 1965 6 hp. lower case?

Thanks in advance for your inputs on this question.

It will work fine.

6tring said:

Can Automotive grade gear lube {Valvoline 80 90w} be safely used on a Johnson 1965 6 hp. lower case?

Thanks in advance for your inputs on this question.

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We are told that outboard gear lube contains corrosion inhibitors and emulsifiers to counteract the effect of water ingress ... otherwise no problem with an automotive gear oil of the same grade.

I always use an automotive oil in my '84 6 hp Evinrude but I am careful to check for (salt) water ingress / change the oil regularly.

Bingo....you guys are right on target. Agreed 100 percent. Keep an eye on any water intrusion....regardless of oil choice. Good to hear from you, Vic.

I was taught is service school that marine oil will not aerate like auto oil as auto is in a vented housing. That the reason it looks like baby poo when you check it after running in yer lower unit.

I was always told "no rear end 80/90 hypoid in a lower unit. Too corrosive on the bronze bushings". An old mechanics tale? I dunno. I do know quite a few GM manual trans the syncros would fail when hypoid oil was used. Gm made a special oil and if none was available, dextron mercon was acceptable. Again those are two different items.

Hypoid? For helical gears? I rebuild manual transmissions, they are loaded with bronze. As brupp mentions....synchro rings. Some use bronze bushings and thrust washers as well. What's the problem? My guess is poor driver operation. Synchros will fail if constantly forcing the transmission into gear where the synchro ring has to work too hard to clutch it's partner gear to the correct speed to mesh with output shaft speed. I really don't believe the failure had much to do with the lubricant. Synchro rings have corrugated rings that grab the machined surface on its gear, these are what wears out. As these wear down, the synchro cannot do is job. There can be a tremendous amount of force applied and gear oil is expected to take the job of preventing wear seriously. These forces are quite similar to the pressure applied to bronze thrust surfaces in a little 6 horse outboard with it's helical gears pushing away from the pinion as power is applied. I really haven't had any gearcase problems over all the years, while using automotive 85/90 weight in my smaller motors to 25 and 30 hp. In fact, my 1978 25 horse has freighted alongside it's 1979 25 hp for over 35 years, using automotive 85/90. The lower unit was rebuilt once....back in 1984, right after I bought it with a stripped out shift dog and gears.....OOPS!! What happened. What did they say in marine school again?....after marine school, I attended 47 years at the "school of hard knocks"!....so far, still haven't graduated either!