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.
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