DB 990 Hydraulic Oil

[Walter Buller]

I am in the process of changing the hydraulic and gear oil in my DB 990. I have always used regular 303 oil for this, but today I read that 15-40 motor oil is best for this purpose. I would appreciate some input on this. Also, that big 1 and 1/8th nut behind the filter. Does that bolt need to be removed to drain that reservoir also? Thanks guys.

 

[RGMartin]

(quoted from post at 20:00:15 09/12/22) Also, that big 1 and 1/8th nut behind the filter.

It is 1 1/4 or 1 5/16" that drains the sump under the differential. Yes it should be pulled.

If your oil is milky, use the cheapest oil you can find, and plan on changing it again. They aren't really picky about oil type. If you don't have a water problem 15W 40 is a good choice.