Confusion: oil grades, yellow metal, vintage

[LouK2]

Hope I'm posting in the right place.

I have a '99 John Deere 4100 tractor and Troybilt tiller of the same year. The JD specifies 75W-90 for the front axle. The tiller specifies 80W-140. But since then Troybilt issued a knowledge article which stated "We have found that 80W-90 GL-1 if full synthetic ..." is OK. Also, I have read other articles on oil grades which seem to imply that on "vintage" equipment and yellow metals, certain grades should not be used because they are corrosive and seem to imply that extreme pressure lubricants should not be used.

All I seem to be able to do at Troybilt is chat with customer service and the nearest service location is an over 100 mile round trip.

I'm confused. I'm not a chemist.

• Is '99 considered "vintage" for the purpose of these articles?
• Does my equipment contain yellow metals?
• I have on hand a quantity of Mobil 1 75W-90 GL-5 full synthetic for the JD. Is this too light for the tiller given the 80W-90 GL-1 specified in the article?

I ask this because it seems easier to find GL-4 or 5 rated oil than GL-1:
• Would GL-5 be harmful given that the original manual said GL-1? Is it all about yellow metal and again, do I have any?

Words cannot express how much I would appreciate help from anyone who can unravel this.

Thanks!

 

[ABN_CBT_ENGR]

Originally Posted by LouK2
Hope I'm posting in the right place.

I'm confused. I'm not a chemist.

• Is '99 considered "vintage" for the purpose of these articles?
• Does my equipment contain yellow metals?
• I have on hand a quantity of Mobil 1 75W-90 GL-5 full synthetic for the JD. Is this too light for the tiller given the 80W-90 GL-1 specified in the article?

Words cannot express how much I would appreciate help from anyone who can unravel this.

Thanks!


If you are confused and not a chemist, you are definitely in the right place.

As far as "vintage"- that's a nebulous term and meaningless

Yellow metals in industry speak is brass/bronze/and possibly copper in whole parts or alloying percentages so if you have synchronizers, bushings, bearings, gears then many EP additives will chemically attack them.

Its not the "grade" or dino V. synthetic- its the EP additive chemistry in question and that's almost blend specific.

That's what you need to go back and find out- do you have bronze parts?

If so you need an oil that is friendly to yellow metals

 

[JayhawkRoy]

Seems your question is answered here. https://support.troybilt.com/s/article/273-1?language=en_US

Looks like the recommendation is to use GL-4 85W-140 or GL-4 SAE 140 gear oil for full replacement, which sounds like what you are doing. GL-1 can be an acceptable substitute (but probably not as readily available.) NAPA shows GL-1 in their catalog if you want to go that route.

ARTICLE NUMBER
000002341
PROBLEM
What lubricant should be used in the tiller transmission case?

SOLUTION
In the past the rule was: For partial fill-ups (a few ounces or less) use SAE 140, SAE 85W-140 or SAE 80W-90 weight gear oil with an API rating of GL-4 or GL-5. For full replacement use SAE 140 or SAE 85W-140 gear oil with an API rating of GL-4 only.

We have also found that 80W-90 oil with an API rating of GL-1 is acceptable for both partial and full replacement of tiller gear oils.

We have 80W-90 lubricant available (12 quart case) at our Online Parts Store as part number 737-04040.

This oil is also available at most automotive supply stores.

 

[ABN_CBT_ENGR]

Originally Posted by JayhawkRoy


PROBLEM
What lubricant should be used in the tiller transmission case?

SOLUTION
In the past the rule was: For partial fill-ups (a few ounces or less) use SAE 140, SAE 85W-140 or SAE 80W-90 weight gear oil with an API rating of GL-4 or GL-5. For full replacement use SAE 140 or SAE 85W-140 gear oil with an API rating of GL-4 only.


We have also found that 80W-90 oil with an API rating of GL-1 is acceptable for both partial and full replacement of tiller gear oils.

We have 80W-90 lubricant available (12 quart case) at our Online Parts Store as part number 737-04040.

This oil is also available at most automotive supply stores.


What that tells you is that the OEM has done no design engineering whatsoever and made general recommendations on either/both historical data or lubrication vendor recommendation then adjusted it at a later time with more of the same.

Whatever you put in there will be fine because this obviously isn't synchronized

 

[doitmyself]

I agree with JayhawkRoy. They seem to be steering you away from using GL5. Both GL1 and GL4 are yellow metal safe.

The John Deere owners manual states GL5.