Generator oil change

Perhaps picky, but there is no such thing as a winter rated 30 weight oil which is what 30w would stand for. But we knew you really meant 30 weight oil------not 30w.

The reason air cooled engine manufacturers often recommend a dine 30 weight oil is that a 10w-30 dino oil will shear down to a 10w-25 or 10w-20 oil after a few hours of use. That could be too thin to lube the engine when under heavy load and in a warm ambient. Their marketing people don't want to burden their customers with a multi-weight synthetic oi (that won't shear down) because of the added expense.

Choosing a good synthetic oil with a multi-vis rating will provide easy starting and quick lube after a start. Meanwhile the higher weight viscosity won't shear down and continue to provide good lube when the engine is hot.

My sons had a commercial lawn mowing business to pay their college expenses. They had 61" and 72" mowers with Kohler air-cooled engines and I used Mobil 1 15w-50 oil in them. I kept the 72" mower when they quit the business and got "real" jobs. It has over 3000 hours on it and running fine.

Besides the 15w-50 oil, Mobil also has a 5w-40 turbo diesel oil that is also rated for spark engine use. Either would be a good choice or similar viscosity from a reputable supplier. Read that to mean Shell, Amoco etc. but not "boutique" brands like Amsoil, Red Line etc.

Napa Gold Filter is part# 7398 made by WIX which is what I always use. I have never heard of putting 0w40 in any ONAN generator. It isn't a 4-wheeler/ATV. Cumminsonan website has a chart of what oil to use depending upon the temperatures you will be running it in ie. 30w for 32-100 degrees.

The filter Onan number for the 5500 genset is 122-0836, and you will need the filter wrench if you want to have any chance to remove the old one as it is recessed and not assessable to a strap type wrench. The part number for the wrench is 420-577. Here is a link to what it looks like.
Onan filter wrench

I just use HD30 from Supertec from Walmart. Good stuff, packaged by mobil. High Detergent too. Let's your genny start out with protection.

I went to the local Cummins dealer and bought the filter and the oil AND the oil filter wrench to get inside where the filter is located.

It was a size wrench I couldn't find anywhere else.

I use a 0W40 mobil one. Good for low temp and the hot 106+ out this way. Can't help you on the filter. Since I have a larger unit.