There are two kinds of Delvac. In the U.S. the silver jug is synthetic and the black jug is mineral. In Canada, that's different. If yours is really noisy and you're feeding it black jug Delvac then I'd suggest trying the silver jug. I believe mine had black jug and was less noisy when I used silver jug. However, it still made some diesel noise in the morning.

Diesels are supposed to make some noise. A quiet diesel may have worn injectors, low compression, etc, etc. When I changed the injectors on my old 603 with 278,000 its now noisier in the morning - the injectors are giving the correct spray pattern....

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Brian Toscano