Typically you should run an additive in your older tractors due to the lack of lubricity in low sulfur fuel. Newer tractors are able to handle the low sulfur diesel because they were engineered for it where as an older diesel experiences more wear in the injection pump because sulfur that is removed acted as a lubricant. I personally use power service. It's good stuff. It's the only additive I've used in the winter where my fuel has not gelled. (I drive semi for a living) For summer time, you need to use the summer formula in the silver bottle and in the winter you use the white bottle. Just my humble opinion.
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